Syria is under mounting pressure to pull its troops out of Lebanon completely and quickly,or will face political and economic isolation in the world community, The Washington Post reported Friday.

The ultimatum will be issued to Syria when Terje Roed-Larsen, atop UN envoy on the Middle East issue, scheduled to meet Syrian President Bashar Assad on Saturday, the Post reported, quoting UN and US officials as saying.

The UN envoy will tell Assad that Syria will face political andeconomic isolation if he does not completely and quickly withdraw from Lebanon, the paper said.

Roed-Larsen plans to inform Syria that the international community is united in insisting that Damascus comply with U.N. Resolution 1559 -- and is prepared to impose wide punitive sanctions if it does not act quickly, the paper quoted officials as saying.

Over the past weeks, the UN envoy has reportedly met with US, European and Arab officials to determine the positions in preparation for the diplomatic confrontation.

Roed-Larsen, according to the report quoting the UN source as saying, will tell the Syrian president to take the following four steps.

First, Syria must honor the independent sovereignty of Lebanon and not undermine its spring elections for a new parliament.

Second, Syria must provide a complete timeline for a full pullout of its troops.

Third, Syria must provide a timeline for the pullout of its 5,000 intelligence agents in Lebanon.

Finally, Roed-Larsen will discuss other requirements in Resolution 1559, including the need to disarm and dismantle foreign and domestic militias operating in Lebanon.

Since the assassination of former Lebanese prime minister RafiqHariri on Feb. 14, Syria has been under strong pressure to be out of Lebanon completely, though it decided to withdraw its troops toeast part of Lebanon from Beirut. Enditem