Russia said it will use its veto in the U.N. Security Council to block any resolution on Syria it considers unacceptable, warning it would not let such a plan pass by abstaining in a vote.

The remarks by Moscow's U.N. envoy, Vitaly Churkin, were the clearest threat yet of a Russian veto on a Western-Arab draft resolution calling for Syrian President Bashar al-Assad to delegate powers to his deputy and end 11 months of bloodshed.

Hours earlier, senior Russian diplomats suggested Moscow would veto the resolution if it is not amended to rule out the possibility it could be used as a pretext for military intervention in Syria.

If the text will be unacceptable for us we will vote against it, of course, Churkin told reporters in Moscow via a videolink from New York.

If it is a text that we consider erroneous, that will lead to a worsening of the crisis, we will not allow it to be passed, he said. That is unequivocal.

Churkin indicated that Russia will fight hard for serious changes to the current draft and, while it hopes for a consensus, is in no rush.

Western and Arab diplomats say they want the council to vote on the draft resolution, which says the body fully supports the Arab League plan for Syria, before the end of the week.

Churkin said there would be no vote until Tuesday at the earliest, and then only if Security Council members are shown a report from an Arab League monitoring mission in Syria this week.

The draft is missing the most important thing: a clear clause ruling out the possibility that the resolution could be used to justify military intervention in Syrian affairs from outside, Interfax news agency quoted Russia's envoy to the European Union, Vladimir Chizhov, as saying. For this reason I see no chance this draft could be adopted.

Deputy Foreign Minister Gennady Gatilov said: We reject ... any attempts to use the Security Council to foster conflict and justify eventual foreign military intervention.

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Syria has given Russia its strongest foothold in the Middle East, buying its weapons and hosting a naval supply and maintenance facility that is Russia's only military base outside the former Soviet Union.

Russia has repeatedly warned it would prevent the Security Council from stamping its approval on potential military intervention in the Arab country.

Last year, Moscow accused the United States and other NATO nations of overstepping the bounds of a March 2011 Security Council resolution that authorized an air campaign in Libya and using it to oust leader Muammar Gaddafi. Moscow allowed the resolution to pass by abstaining in a vote.

Western and Arab pressure for U.N. action on Syria is driven by alarm over the killing of thousands of people since Assad's government began a crackdown on pro-democracy protests nearly a year ago.

British Foreign Secretary William Hague told the council on Tuesday the resolution does not call for military action and could not be used to authorize it. French Foreign Minister Alain Juppe described the idea of such intervention as a myth.

The comments by Russian diplomats suggest Moscow would not settle for such assurances and would lobby for clear language.

As of today, the content of the draft resolution is not acceptable to us because it continues to include clauses that contain the introduction of sanctions against Syria and also clauses that can be interpreted as an opportunity to use force, Gatilov said, according to Interfax.

Moscow says the West took advantage of fuzzy wording in the Libya resolution to turn a mandate to protect civilians into a push for regime change that led to Gaddafi's overthrow.

Russian diplomats have also suggested Moscow could use its veto if the expression of support for the Arab League plan that calls for Assad to cede power is not removed from the draft.

In addition, Russia has voiced concern that the draft's threat of further measures if Syria fails to implement the resolution could lead to sanctions, which it opposes.

Churkin said Russia was categorically against any arms embargo on Syria.

It seems logical: if there is a conflict, let's not deliver arms. But we saw what happened in Libya, he said.

It was forbidden to deliver arms to the government but anyone under the sun delivered (to) armed opposition groups, that is what it meant in practice.

How then can we break contracts, our years-old relationship which we have with Syria ... especially when what we are delivering is not what can be used to shoot demonstrators, he said.

Russia and China joined forces in October to veto a Western-drafted resolution that would have condemned Assad's government and threatened possible sanctions.

(Writing by Steve Gutterman; Editing by Janet Lawrence)