Ambassadors of the 15 UN Security Council members met behind closed doors on Saturday mooring for an unusual weekend session to consider an Arab- European draft resolution which backs an Arab League plan to promote political transition in Syria.

The ambassadors first gathered for the closed consultations on the draft resolution, instead of meeting in an open session as previously scheduled at 10 a.m. EST (1500GMT) on Saturday, with pressures from the Western countries for an early vote.

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

The U.S. permanent representative, Susan Rice, told reporters before she entered into the Security Council chamber for the closed consultations that she is opposed to any change to the draft which the council members agreed to send to their capitals for further instructions.

However, Russia, a veto-wielding member, on Saturday insists the revised be perfected on two crucial problems before getting a nod from Moscow.

On the Russian proposed amendments, Rice said that "they are unacceptable."

For his part, French UN Ambassador Gerard Araud said that they are determined to go ahead with the vote on the draft resolution despite strong opposition from Moscow.

If the Security Council puts the draft to vote on Saturday, there is 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 members of the Security Council -- 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 its strong opposition to the draft resolution, tabled on 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 the four-hour hard negotiations at the council behind closed doors 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, vetoed a European draft resolution on Syria in October 2011.

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 "full supports" the Arab League plan which demands a political transition in Syria.

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