Ambassadors of the 15 U.N. Security Council members gathered Saturday for an unusual weekend session to consider an Arab-European draft resolution that backs an Arab League plan to promote political transition in Syria.

The council was scheduled to meet in open session at 10 a.m. EST (1500GMT) Saturday, with pressure from Western countries for an early vote.

Arab and Western nations revised the draft resolution to take into account the concerns of Russia, which opposes any foreign military intervention in Syria.

However, Russia, a veto-wielding council member, on Saturday insisted that the revisision be perfected on two crucial issues before getting a nod from Moscow.

If the Security Council puts the draft to vote on Saturday, there was no guarantee that it will be adopted.

In order to be adopted, a draft resolution needs nine votes in favor and no veto from any of the five permanent council members -- Britain, China, France, Russia and the United States.

"We are not saying this resolution is hopeless," Russian Foreign Minister Sergei Lavrov said during a panel discussion at the Munich Security Conference.

"We circulated an amended resolution which aims to fix two basic problems ...(first), the imposition of conditions on dialogue, and second, measures must be taken to influence not only the government but also armed groups," the foreign minister said, adding that these two issues are "of crucial importance" from the view of Russia.

Earlier this week, Russia voiced strong opposition to the draft resolution, tabled Friday last week by Morocco, a non-permanent member of the council. The draft was jointly drawn up by Arab states, Britain, France and Germany.

At the end of four hours of closed negotiations at the council on Thursday, sponsors of the draft dropped a specific reference to Syrian President Bashar al-Assad's ceding of power.

The revision was made in order to avoid a veto by Russia, which, together with China, blocked a European draft resolution on Syria in October.

According to the revised copy of the draft resolution, which was sent to governments of the council members and obtained by Xinhua, the Security Council "fully supports" the Arab League plan that demands a political transition in Syria.

Russia has warned some countries against meddling in the internal affairs of Syria out of concern that the draft resolution contains what is seen to promote "regime change" in the Middle East country.