The adoption of a tough, new Western-backed UN resolution on Syria would amount to "direct support" for opponents of embattled Syrian President Bashar al-Assad, Russia's foreign minister said ahead of a Security Council vote later on Wednesday.

"To adopt the resolution would be...direct support for the revolutionary movement," Sergei Lavrov told journalists. "To pressure just one side means drawing [Syria] into a civil war and interference in the internal affairs of the state."

Just hours before the UN vote, Syria's defense minister was killed in a suicide bombing at the national security building in Damascus, as heavy fighting continued to rage in the capital, Syrian state television said. The rebel Free Syria Army said earlier this week it had launched the final battle for control of Damascus.

The draft resolution to be discussed on Wednesday gives the Syrian government 10 days to pull out heavy weapons from urban areas and return troops to barracks. If Damascus fails to comply, a further resolution on sanctions will be submitted to the Security Council.

Russia’s UN envoy, Vitaly Churkin, said ahead of the Security Council meeting that Moscow would use its veto to block any resolution that called for the removal of Assad.

Russian President Vladimir Putin vowed earlier this year not to allow a repeat of the “Libya scenario,” a reference to the ouster and murder of long-time Libyan dictator Muammar Gaddafi after a NATO military campaign. Both Russia and China have blocked previous UN resolutions against Assad’s regime, which the United Nations has accused of complicity in the massacre of unarmed civilians.

UN special envoy Kofi Annan met with Putin in Moscow on Tuesday in an attempt to persuade Russia to drop what Western powers has said is the Kremlin's support for Annan, but his trip appeared to produce few tangible results. Russia has said it has no interest in seeing Assad remain in power, but insists that any decision on his ouster should be taken by "the Syrian people."

Moscow proposed on Wednesday that Annan call a second round of talks on Syria, including an invitation to Iran and Saudi Arabia, who were excluded from a meeting last month in Geneva. The five permanent members of the UN Security Council - the U.S., Russia, China, Britain and France – agreed on June 30 in Geneva that a transitional government should be set up in Syria. The text of the document said this could include members of the government and opposition, although Russia later objected to U.S. suggestions that the deal ruled out any role for Assad.

"We proposed that Annan form another action group," Lavrov said. "We said once again it would be good to correct the error made in Geneva when Iran and Saudi Arabia were not invited."

The United Nations, quoting Syrian rights activists, says some 16,000 people have died in Syria since the start of the revolt.