Reuters news reported that Free Syrian Army fighters said that they have shot down a government helicopter over the capital, the first indication that the Free Syrian Army possesses advanced weapons that can challenge Assad’s air force.

"Helicopters are flying at low altitude. It's easy to target them using anti-aircraft weapons," a senior rebel officer told Reuters. An activist and another rebel fighter also said the helicopter was brought down in Qaboun, in northeast Damascus.

Meanwhile, Syrian rebels fighting the regime forces in Damascus said Tuesday that the "battle for the liberation" of the capital had begun and that it would end after the conquest of the city.

"The battle for the liberation of Damascus began and fighting will not stop in the capital. We are going to win," said Colonel Kassem Saadelddine, spokesman for the Free Syrian Army (FSA).

"We transferred the battle from the provinces to the capital. We have a clear plan to control all Damascus," he added. "Expect some surprises," he warned without elaborating.

On the diplomatic front, the Russian President Vladimir Putin said during the meeting with Mr. Kofi Annan in Moscow on Tuesday that Moscow will do its best to support Kofi Annan`s 6-point peace plan on Syria.

"From the very beginning, since the first measurements, we support and continue to support your efforts to restore peace" in Syria, said Vladimir Putin.

"I can assure you that we will do everything to support your efforts," the Russian leader added.

For his part, Annan told Putin that the Syrian crisis has reached a critical point and that he was glad to have the opportunity to talk about it.

Earlier, Russian media said that the Kremlin is any sanctions on Syria, the Kommersant daily wrote.

Kommersant said that during a meeting last week with Russian diplomats, Putin ordered them to defend international law, whatever the cost.

For it's part, the Vedomosti daily criticized the difference in the Russian position towards Libyan crisis and Syrian violence. At that time, Russian foreign minister said Libyan leader should go even though the number of victims less than the number of victims in Syria. However, this sounds weird as both countries had good relationships with Syria on social and military basis.

In related news, the meeting between the Russian President and Kofi Annan took place on the eve of the introduction by the U.S., the U.K., France and Germany of a new draft resolution at the U.N. Security Council. The resolution would authorizes sanction against Syrian regime if it fails to stop violence within 10 days.