Witnesses and the state-run SANA news agency said two children have been killed and 10 others injured. Meanwhile, UN observers have entered the central Syrian village of Tremseh, two days after activists said about 220 people had been killed there.

As the violence continues, UN observers are investigating the latest reported massacre.

The 11-strong convoy headed for the central village of Tremseh after receiving confirmation a cease-fire was in place.

Much remains unclear about what happened in the village.

Activists said over 200 people were killed by government forces.

If confirmed, it would be the bloodiest assault in Syria since the fighting began 16 months ago.

However, the Syrian government said the attack was a successful military operation that killed many "terrorists" but no civilians.

State television also showed weapons, documents and equipment such as gas masks and binoculars that were apparently seized by the army during the operation.

The massacre has prompted international outrage.

Tayyip Erdogan, Turkish Prime Minister, said, "There are no words left to say for Syria. Such vile massacres, such attempts of genocide and such inhumane violence are footsteps of a government that is on its way out."

Chinese Foreign Ministry spokesman Liu Weimin said in a statement that China strongly condemns the killing of innocent civilians.

He said China hopes that a thorough investigation into the killings will be launched and that those responsible for the abuses will be duly punished.

UN Secretary-General Ban Ki-moon and international envoy Kofi Annan also condemned the attack.

They're calling on the UN Security Council to demand a halt to the escalating violence in Syria and to make clear their would be "consequences" if the conflict continues.