The UN Security Council will hold an emergency session Saturday, March 15 to vote on a Western-backed resolution denouncing the upcoming referendum in Crimea on switching over to Kremlin rule, diplomats said Friday, according to Agence France-Presse.

The meeting, which is set to begin at 11:00 am (1500 GMT), was called at Washington's request. Diplomats say they expect Russia to veto the resolution.

The position of veto-wielding China -- which often backs Russia at the council, especially on Syria-related votes -- is more uncertain this time around, one Western diplomat said. Beijing has long defended the need to respect territorial integrity and does not back interference in the internal affairs of other countries. "The only objective of a resolution would be to get the Chinese to abstain and isolate Russia further," another council diplomat said. The resolution was drafted by the United States in very measured terms so that it could be accepted by Beijing.

It does not target Russia specifically and does not explicitly call for Russian troop reinforcements to withdraw from Ukraine's Crimean peninsula, where Moscow has military bases. It also does not threaten sanctions.

From a tactical point of view, Western diplomats hope the council will back the resolution before the referendum takes place on Sunday in the autonomous region that has a large ethnic Russian population.

After the vote, Western powers will ratchet up their criticism of Russia to an extent that China is unlikely to find comfortable. They also wanted to wait on the outcome of last-ditch talks between US Secretary of State John Kerry and his Russian counterpart Sergei Lavrov, which broke up in London earlier in disagreement.

The draft resolution declares that the referendum "can have no validity and cannot form the basis for any alteration of the status of Crimea." It calls on states to refrain from recognizing the result and from "any action or dealing that might be interpreted as recognizing any such altered status." It is a convoluted formula to demand that Russia not annex Crimea.

The resolution also reaffirms commitment to the "sovereignty, independence, unity and territorial integrity of Ukraine within its internationally recognized borders."

The text calls on Moscow and Kiev to hold direct talks and exercise restraint, and notes the willingness expressed by interim authorities in Kiev to protect the rights of all Ukrainians, including minorities.

This is a concession to Moscow, which says Russian speakers in eastern Ukraine have been threatened.