A military unit from Russia, President Bashar al-Assad's best and last friend, has arrived in Syria, Russian media reported Monday.

Russia has repeatedly blocked the United Nations Security Council's attempts to halt the violence, accusing the U.S. and its allies of trying to start another war.

Now the Russian Black Sea fleet's Iman tanker has arrived in the Syrian port of Tartus with an anti-terror squad from the Russian Marines aboard, ABC News said Russia's Interfax news agency reported. The Russian news reports did not elaborate on the troops' mission in Syria or if they are expected to leave the port.

The Iman replaced another Russian ship which had been sent to Syria to demonstrate the Russian presence in the turbulent region and possible evacuation of Russian citizens, the Black Sea Fleet told Interfax.

RIA Novosti, a news outlet with close ties to the Kremlin, trumpeted the news only on its Arabic language site. The Russian Embassy to the U.S. and to the U.N. had no comment, saying they have no particular information on the arrival of a Russian anti-terrorism squad to Syria.

Last week Russia's Foreign Minister Sergei Lavrov said Russia had no plans to send troops to Syria.

The presence of Russian troops in Syria could be a pretty obvious show of support to the regime, said security expert Mark Galeotti.

No one thinks of the Russians as anything but Assad's last friends, Galeotti, professor of global affairs at New York University, told ABC.

Meanwhile, Syrian rebels fought gun battles with government forces in Damascus Monday, in the most violent clashes the capital has seen since the start of the revolt a year ago.

In yet another attempt to form a united international front on the mounting crisis, France circulated a draft for the U.N. Security Council deploring the turmoil and backing peace efforts by U.N.-Arab League envoy Kofi Annan, Reuters reported. Britain's U.N. representative said he hoped the statement would be adopted Tuesday.

Piling further pressure on the Assad government, its ally Russia urged both sides to agree to daily truces, backing an initiative from the International Committee of the Red Cross to reach the wounded.

But neither government forces nor armed rebel movements showed any sign of bowing to calls for restraint.

The clashes in Damascus on Monday came just two days after two car bombs killed at least 27 people in the heart of the city, in a sign that the capital, once isolated from the bloodshed, might be starting to sink into the mayhem.

The fighting near the center of Assad's power appeared to be an attempt by rebels to show they still pose a serious challenge after being forced out of strongholds in recent weeks.

Reports from Syria cannot be independently verified because authorities have barred access to rights groups and journalists.

Opposition elements in Dir al-Zur posted a video Monday they said shows Syrian soldiers throwing dead and injured civilians from rooftops, Israel's Ynet News reported.

The British-based Syrian Observatory for Human Rights said up to six rebels had fired a rocket-propelled grenade at the house of an army general in Damascus before taking refuge in a building during a fierce gunfight.

The official Syrian news agency SANA said the authorities had stormed a terrorist hideout and that three rebels and one member of the security forces were killed in the raid.

These clashes were the most violent and the closest to the security force headquarters in Damascus since the outbreak of the Syrian revolution, said SOHR director Rami Abdu.