UNITED NATIONS - Arab nations have dropped an explicit demand for President Bashar al-Assad to quit from a resolution on the Syria conflict to be voted at the UN General Assembly on Friday.

With the international community reeling from the resignation of UN-Arab League envoy Kofi Annan, the Arab League and their western supporters are confident the resolution will be passed in the 193-member assembly. But they have toned it down in a bid to get as big a majority as possible.

Faced with opposition from some Arab and Latin American countries, the resolution, drawn up by Saudi Arabia, has been stripped of the demand for Assad to stand down and for the wider application of sanctions ordered by the Arab League.

Russia and China, which have vetoed three UN Security Council resolutions that could have led to sanctions against Assad's government, are expected to vote against the text.

No country can veto a resolution in the General Assembly however. A resolution passed by 137 votes to 12 on February 16 led to the creation of the special envoy's post that Annan was named to.

The draft resolution condemns the Syrian government's use of "heavy weapons" and its failure to withdraw troops and artillery from towns in line with the peace plan that Assad agreed with Annan but has never carried out.

Syrian activists say that more than 20,000 people have been killed since an uprising against Assad erupted in March 2011.

The text demands that Syrian authorities stick to their "obligations" under international law which ban the use of chemical weapons and that all sides in Syria "implement rapidly" a political transition plan agreed by the international powers on June 30.

"The aim is to increase pressure on the Assad government. We want as many people to back this which is why some changes have been made," one Arab diplomat said ahead of the vote.

Other diplomats said the initiative is a reflection of the international frustration and anger felt at the failure of moves to put pressure on the Syrian government, particularly the vetos by Russia and China.

French Foreign Minister Laurent Fabius has already offered his "strong" support to the Arab moves at the United Nations.

France's UN ambassador, Gerard Araud, Security Council president for August, said the resolution would show that Russia and China are a "tiny minority" at the UN General Assembly.

The draft text deplores "Security Council failure to agree on measures" on Syria and the growing use of tanks, helicopters and other heavy weapons by the Syrian authorities.

It calls for the establishment of a "consensus transitional governing body" in Syria, which hints at the need for Assad to stand down, and for free elections.