The opposition Syrian National Council renewed on Saturday its call for the United Nations to intervene militarily in the country to put a stop to "crimes" by President Bashar al-Assad's regime.

"We call anew on the UN Security Council to act with all urgency to intervene militarily to bring an end to the crimes committed by the bloody regime against the unarmed Syrian people," said a statement received in Beirut.

The plea came as the SNC claimed that government forces entered the Homs neighbourhood of Bayyada on Saturday and that the "streets and houses were full of the bodies of martyrs and the destruction terrifying."

Since the beginning of the year, troops have been pounding the central city in a bid to retake rebel-held districts.

The SNC appealed to UN observers who arrived on Sunday to go immediately to Homs "to try to stop the crimes of the regime," claiming that Bayyada and another neighbourhood, Khaldiyeh, "are the target of barbaric shelling and an inhumane embargo."

While Homs has been a regular target of bombing, an activist there, Khaled Tellawi, told AFP in Beirut the bombing had stopped and that "the area was calm" on Saturday, possibly indicating an imminent visit by observers.

On Thursday, the rebel Free Syrian Army called for outside military intervention even without UN backing to carry out surgical strikes on key regime installations.

Monitors say more than 200 people have been killed in Syria since a shaky ceasefire to which the government and rebels committed themselves went into effect on April 12.