BEIRUT, Lebanon — Fierce fighting on the battlefield and setbacks on the diplomatic front increased pressure on the embattled Syrian government as fresh signs emerged on Tuesday of a sustained battle for control of the capital, Damascus.
News reports quoted activists as saying that fighting was raging in the southern suburbs of Damascus and near the international airport for a fifth straight day as government forces sought to dislodge rebels and reverse their recent gains.
While the government has superior firepower and rebels are reporting heavy losses, loyalist forces have been carrying out a serious counteroffensive in the suburbs without being able to subdue the insurgents.
The latest reports followed developments on Monday when a senior Turkish official said that Russia had agreed to a new diplomatic approach to seek ways to persuade President Bashar al-Assad to relinquish power, a possible weakening in Russia’s steadfast support for the Syrian government.
In Damascus, a prominent Foreign Ministry spokesman was said to have left the country amid reports of his defection, and President Obama and Secretary of State Hillary Rodham Clinton issued warnings that any use of chemical weapons by a desperate government would be met with a strong international response. The NATO secretary general, Anders Fogh Rasmussen, echoed this warning on Tuesday.
“The possible use of chemical weapons would be completely unacceptable to the whole international community,” Mr. Rasmussen said, according to Agence France-Presse.
A Western diplomat confirmed that there were grave concerns in United States intelligence circles that Syrian leaders could resort to the use of the weapons as their position deteriorates.
The Syrian Foreign Ministry, repeating earlier statements, told state television that the government “would not use chemical weapons, if it had them, against its own people under any circumstances.”
The United Nations said it was withdrawing nonessential international staff from Syria, and the European Union said it was reducing activities in Damascus “to a minimum,” as security forces pummeled the suburbs with artillery and airstrikes in a struggle to seal off the city from its restive outskirts and control the airport road. A senior Russian official spoke for the first time in detail about the possibility of evacuating Russian citizens.
The United Nations World Food Program reported on Tuesday that “the recent escalation of violence in Syria is making it more difficult to reach the country’s hardest-hit areas.”
“Food insecurity is on the rise due to bread shortages and higher food prices in many parts of the country. High prices are also affecting neighboring countries hosting Syrian refugees,” the organization said in a statement.
“Road access to and from Damascus has become more dangerous, making it difficult to dispatch food from World Food Program warehouses to some parts of the country, the organization said, adding that there had been increasing indiscriminate attacks on its trucks in different parts of the country.
It also said it would relocate seven nonessential staff members to neighboring Jordan while about “20 international and 100 national W.F.P. staff remain in the country to carry out the emergency operation to feed 1.5 million vulnerable Syrians.” Mr. Assad has held on longer than many had predicted at the start of the 21-month uprising. He still has a strong military advantage and undiminished support from his closest ally, Iran. Military analysts doubt the rebels are capable of taking Damascus by force, and one fighter interviewed on Monday said the government counteroffensive was taking a heavy toll. There were still no firm indications from Russia that it was ready to join Turkey and Western nations in insisting on Mr. Assad’s immediate departure.
But the latest grim developments follow a week of events that suggested the Assad government was being forced to fight harder to keep its grip on power. Rebels threatened its vital control of the skies, using surface-to-air missiles to down a fighter plane and other aircraft. The opposition also gained control of strategic military bases and their arsenals, and forced the government to shut down the Damascus airport periodically. The Internet was off for two days.
A Russian political analyst with contacts at the Foreign Ministry said that “people sent by the Russian leadership” who had contact with Mr. Assad two weeks ago described a man who has lost all hope of victory or escape.
“His mood is that he will be killed anyway,” Fyodor Lukyanov, editor of a Russian foreign affairs journal and the head of an influential policy group, said in an interview in Moscow, adding that only an “extremely bold” diplomatic proposal could possibly convince Mr. Assad that he could leave power and survive.
“If he will try to go, to leave, to exit, he will be killed by his own people,” Mr. Lukyanov said, speculating that security forces dominated by Mr. Assad’s minority Alawite sect would not let him depart and leave them to face revenge. “If he stays, he will be killed by his opponents. He is in a trap. It is not about Russia or anybody else. It is about his physical survival.”
Many observers — United Nations personnel in Syria, Arab diplomats and opposition activists — stress that it is difficult to reliably assess the state of the government. But taken together, the day’s events suggested that the government’s position was declining more sharply than it had in months and that an international scramble to find a solution to the crisis was intensifying.
Nabil al-Araby, the head of the Arab League, said on Monday that the government could fall at “any time,” Agence France-Presse reported.
The Arab League has long called for Mr. Assad to step down. But Russia, Mr. Assad’s most powerful ally, has held out the possibility of his staying in power during a transition, so the Russian government’s apparent shift of emphasis carried more weight.
Mikhail Bogdanov, a deputy foreign minister, told Itar-Tass that Russia was ready to provide assistance to any of its citizens wishing to leave Syria. Tens of thousands of Russians live there, mainly women married to Syrian men after years of cold-war cooperation between the countries. He said their route out would most likely be by plane.
After meeting in Istanbul on Monday, President Vladimir V. Putin of Russia and President Recep Tayyip Erdogan of Turkey said they had agreed on a new approach to resolving the conflict.
“We are neither protecting the regime in Syria nor acting as their advocate, but remain worried about Syria’s future,” Mr. Putin said at a joint news conference with Mr. Erdogan.
Mr. Putin did not elaborate, though Mr. Bogdanov said Russia would meet intensively with Syrian opposition groups based inside the country in the coming month. A senior Turkish official, speaking anonymously in accordance with diplomatic protocol, said plans included looking for ways to get Mr. Assad to step down. Russia has previously said it is not wedded to Mr. Assad, but the official suggested it was now more motivated to find an alternative.
“There is definitely a softening of the Russian political tone,” the Turkish official said, adding that Mr. Putin had acknowledged that Mr. Assad seemed unwilling to depart.
Yet, doubts remain about whether Russia can engineer a breakthrough. The Kremlin has insisted the crisis would be resolved only through negotiations between Syria’s government and its opponents, and its top envoy to Syria has quietly continued to meet with defectors from Mr. Assad’s government and members of the opposition.
But Russia has typically engaged mainly with Syria-based opposition groups, which the exile opposition and many in the uprising say are too close to the government
Lebanon’s Al-Manar television reported that a Syrian Foreign Ministry spokesman, Jihad Makdissi, had been fired for making statements that did not reflect the government’s position. Activists said he had defected.
Mr. Makdissi, whose polished persona and fluent English had long made him one of the most cosmopolitan faces of the government, had not taken reporters’ phone calls or made public statements recently.
Rami Abdul-Rahman, who uses a pseudonym for safety reasons and is the director of the Syrian Observatory for Human Rights, based in Britain, said that Mr. Makdissi had met his family in Beirut, where they had been staying, and was believed to have boarded a flight for London. He said Mr. Makdissi had earlier angered some in the Syrian government with a statement saying Syria would use chemical weapons only against a foreign invasion — weapons the government prefers not to acknowledge it has.
Analysts say the rebels are forcing the government to devote forces to Damascus, and their offensive could hasten the loss of control in other parts of the country.
“We feel a change in the security situation,” said Muhannad Hadi, the Syria director of the World Food Program. “You hear sounds of explosions, you hear shelling, you don’t know where it’s taking off or where it’s landing,” Mr. Hadi said. “It’s becoming part of daily life.”
Anne Barnard reported from Beirut, Lebanon, and Ellen Barry from Moscow. Reporting was contributed by Alan Cowell in London, Sebnem Arsu in Istanbul, Peter Baker in Washington, Hwaida Saad, Neil MacFarquhar and Hania Mourtada in Beirut, and Christine Hauser in New York.