Russia has sent warships to the Mediterranean in preparation for an evacuation of its citizens from Syria, according to a Moscow news agency.
The move is the first sign that Russia, a key ally of Syrian President Bashar al-Assad, is worried that rebel advances now threaten the capital Damascus.
Moscow’s actions come just a day after rebels seized the Yarmouk Palestinian camp two miles from the city centre. The camp is considered to be a possible springboard for a thrust into Damascus.
Although the anti-Assad opposition has waged a 21-month-old uprising, its most significant military and diplomatic gains have come in last few weeks.
It has recently captured a series of army installations across Syria and secured formal recognition from Western and Arab states for its new coalition.
Assad's allies have largely stood behind but Russia, his main arms supplier, has appeared to waver this week, issuing contradictory statements repeating opposition to Assad stepping down and airing concerns about a possible rebel victory.
Russia's Interfax news agency quoted unnamed naval sources as saying that two assault ships, a tanker and an escort vessel had left a Baltic port for the Mediterranean Sea, where Russia has a port in Syria's coastal city of Tartus.
“They are heading to the Syrian coast to assist in a possible evacuation of Russian citizens ... Preparations for the deployment were carried out in a hurry and were heavily classified,” the agency quoted the source as saying.
It was not possible to independently verify the report, which came a day after Russia confirmed that two citizens working in Syria were kidnapped along with an Italian citizen.
In Damascus, activists reported overnight explosions and early morning sniper fire around the Palestinian refugee camp of Yarmouk.
The Yarmouk and Palestine refugee “camps” are actually densely populated urban districts home to thousands of impoverished Palestinian refugees and Syrians.
“The rebels control the camp but army forces are gathering in the Palestine camp and snipers can fire in on the southern parts of Yarmouk,” rebel spokesman Abu Nidal said by Skype.
“Strategically, this site is very important because it is one of the best doors into central Damascus. The regime normally does not fight to regain areas captured any more because its forces have been drained. But I think they could see Yarmouk as a red line and fight back fiercely.”
Syria hosts half a million Palestinian refugees, most living in Yarmouk, descendants of those admitted after the creation of Israel in 1948, and has always cast itself as a champion of the Palestinian struggle, sponsoring several guerrilla factions.
The battle in Yarmouk was one of a series of conflicts on the southern edges of Damascus, as rebels try to choke off the capital to end 42 years of rule by the Assad family, who belong to the minority Alawite sect, derived from Shi'ite Islam.
Both Assad's government and the mainly Sunni Muslim rebels have enlisted and armed divided Palestinian factions as the uprising mushroomed from street protests into a civil war.
Streams of refugees have fled Yarmouk, the Syrian Observatory for Human Rights said. Many have headed to central Damascus while hundreds more have gone across the frontier into Lebanon.
More than 40,000 people have died in Syria's conflict, activists say. Around 200 died yesterday alone, according to the British-based Observatory, which has a network of activists across Syria. Violence has risen sharply, and with it humanitarian conditions are deteriorating.
The World Health Organisation said around 100 people were being admitted daily to the main hospital of Damascus and that supplies of medicines and anaesthetics were scarce.
It also reported a rise in cases of extreme hunger and malnutrition coming from across Syria, including the rebel-dominated rural areas outside the capital, where the army has launched punishing air raids.
Aid organisations say fighting has blocked their access into many conflict zones, and residents in rebel-held areas in particular have grappled with severe food and medical shortages.
Fighting raged across Syria today, with fighter jets and ground rockets bombarding rebel-dominated eastern suburbs of the capital and army forces shelling a town in Hama province after clashes reignited there over the weekend.
Rebels overran at least five army sites in a new offensive in Hama yesterday, opposition activists said.
Qassem Saadeddine, a member of the newly established rebel military command, said on Sunday fighters had been ordered to surround and attack army positions across Hama province. He said Assad's forces were given 48 hours to surrender or be killed.
In 1982 Hafez al-Assad, late father of the current ruler, crushed an uprising in Hama city, killing up to 30,000 civilians.
Qatiba al-Naasan, a rebel from Hama, said the offensive would probably bring retaliatory air strikes from the government but said that rebels were keen to put more strain on the army as living conditions deteriorated in the province.
“For sure there will be slaughter - if the army wants to shell us, many people will die,” he said by Skype. “But at the same time our situation is already getting miserable. ”
Syrian Vice President Farouq al-Sharaa said in a newspaper interview published on Monday that neither Assad's forces nor rebels seeking to overthrow him can win the war.
Sharaa, a Sunni Muslim in a power elite dominated by Assad's Alawites, is not part of the president's inner circle directing the fight against Sunni rebels but is the most prominent figure to say in public that Assad would not prevail.