Syrian opposition activists say more than 150 people died after government forces shelled a village in Hama province Thursday.

Activists and witnesses say troops, tanks and helicopters bombarded the village of Treimsa, killing many civilians. Estimates of the number of deaths are as high as 220.

State-run Syrian media say troops battled an armed group in the area and, as in previous mass killings, blamed the massacre on those it calls terrorists.

U.S. Secretary of State Hillary Clinton said Friday that credible reports provided indisputable evidence that the regime deliberately murdered innocent civilians.

The reported massacre comes as the U.N. Security Council debates imposing tough new sanctions on the Syrian government if it keeps attacking civilians with heavy weapons.

Russia is threatening to veto the Western-backed resolution. It wants to simply extend the mandate of the U.N. observer mission in Syria for another three months.

Russian media say Annan will visit Moscow on Monday for talks on Syria.