DAMASCUS - Syria has rejected claims by the UN that it used heavy weapons in an attack on the village of Tremseh on Thursday.

It accused UN and Arab League special envoy Kofi Annan of "rushed" comments, adding that only troop carriers and small arms were used in the operation.

Syria said what occurred were armed clashes, not a massacre, with only 37 recorded deaths - far short of the 200 or so deaths activists have suggested.

UN observers have returned to Tremseh to continue investigations.

They still need to determine how many people died, who they were and exactly who carried out the attack.

Syrian foreign ministry spokesman Jihad Makdissi told a news conference in Damascus that no helicopters, aircraft or armoured tanks were used in the attack - only troop carriers and small arms, including rocket-propelled grenades.

He said Mr Annan had sent a letter to the foreign ministry on Saturday that "did not rely on facts".

Mr Makdissi said five buildings housing what he termed "armed terrorists" had been targeted.

He cited the initial findings of the UN observers as supporting the Syrian government's account that armed rebels had been targeted.

However, the observers had confirmed that heavy weapons were used, in violation of a commitment given to Mr Annan by the Syrian authorities.

Mr Makdissi said if any heavy weapons were used it was by the rebel side.

Some activists and witnesses say more than 200 civilians were killed in an indiscriminate massacre, initially by an army bombardment then by pro-government shabiha militiamen who swept into the village and killed people one by one.

The BBC's Jim Muir, in neighbouring Lebanon, says the conclusions of UN observers have so far been more in line with the government's version of events than with reports of an indiscriminate massacre of civilians.

He says the Tremseh killings appear to differ from the situation at Houla two months ago, when UN observers were able to arrive quickly and count the bodies of what was clearly a massacre.

Reports of casualties often cannot be independently verified, as Syria severely restricts journalists' freedom of movement.

Some 16,000 people are thought to have been killed since the uprising against Bashar al-Assad's regime began in March 2011.