Annan says 'appalled' over Tremseh massacre

In a statement condemning the "atrocities", Annan voiced shock at the "intense fighting, significant casualties, and the confirmed use of heavy weaponry such as artillery, tanks and helicopters".

UN observers deployed in Syria stood ready to go to Tremseh to verify the facts "as and when circumstances permit", but would require freedom of movement to do their job, he said.

Syrian activists have posted videos they say show at least 17 of the dozens of people reportedly killed in heavy government shelling of a farming village in central Syria on Thursday.