The Syrian army killed at least 23 civilians in two protest cities on Saturday, a watchdog said, as an international outcry mounted over a massacre in a central village.

UN observers who visited the village of Al-Kubeir, near Hama, said they witnessed blood on the walls and "a strong stench of burnt flesh," prompting Western governments to launch a push for tough new sanctions against Damascus.

Nine women and three children were among 17 people killed in a pre-dawn bombardment of a residential neighbourhood of the southern city of Daraa, the Syrian Observatory for Human Rights said.

Dozens more were wounded, some of them seriously, in the city which was the birthplace of the uprising against President Bashar al-Assad's rule which erupted in March last year, the British-based watchdog said.

In nearby Jordan, hundreds of Syrian refugees demonstrated at dawn in the border town of Ramtha to protest against the deaths in Daraa, Jordan's official Petra news agency reported.

Protesters marched to the Omari mosque in Ramtha, home to around 20,000 Syrian refugees, most of whom hail from Daraa province, Petra said.

In central Syria, government forces pounded several rebel neighbourhoods of the flashpoint city of Homs with artillery and mortars, killing six civilians, the Observatory said.

Diplomats in New York said Britain, France and the United States would quickly draw up a Security Council resolution proposing sanctions against Syria following a grim report from UN monitors on their visit to the village of Al-Kubeir following Wednesday's assault.

"We will move fast to press for a resolution," one UN diplomat said.

More than 20 unarmed UN observers were allowed into Al-Kubeir on Friday, a day after they were shot at and prevented from entering the village.

"Inside some of the houses, blood was visible across the walls and floors. Fire was still burning outside houses and there was a strong stench of burnt flesh," UN spokesperson Martin Nesirky said in New York, delivering a grisly account of the visit.

At least 55 people were killed, according to the Syrian Observatory.

UN officials were unable to confirm the death toll but made clear they believe government forces and their allies were behind the attack on the mainly Sunni Muslim village surrounded by an Alawite population loyal to Assad.

"Armoured vehicle tracks were visible in the vicinity. Some homes were damaged by rockets from armoured vehicles, grenades and a range of calibre weapons," Nesirky said.

UN chief Ban Ki-moon told the Security Council that according to preliminary evidence, troops had surrounded Al-Kubeir and militia entered the village and killed civilians with "barbarity".

Damascus denied responsibility and blamed foreign-backed "terrorists," as it has done repeatedly in the past.

Violence on Friday killed at least 68 people nationwide -- 36 civilians, 25 soldiers and seven rebel fighters, the Observatory said. More than 13,500 people have been killed since the start of the uprising.

Opposition regroups

Leaders of the exiled Syrian National Council met in Turkey on Saturday to pick a new leader after the resignation of Burhan Ghalioun last month to avert divisions in the opposition bloc.

Ghalioun resigned on May 17 after activists accused him of ignoring the Local Coordination Committees, which spearhead anti-government protests on the ground, and of allowing the Muslim Brotherhood to play a leading role within the bloc.

Sources in the group said the aim was to pick a "consensus" candidate who would be acceptable to Islamists, liberals and nationalists.

"There is a consensus inside the council that there should be a rotating presidency, so we are now changing the president for the coming three months," said Bassma Kodmani, the SNC spokeswoman for external relations.

The new leader will face the challenge of boosting the SNC's credibility with activists and rebel fighters inside Syria as well as the international community.

Prior to the meeting, leaders of the armed opposition called on the international community to provide them with better weaponry and support.

"Those who claim to support the Syrian opposition should begin by supporting people on the inside of Syria," said Hussein Sayyed, head of the Supreme Council for the Leadership of the Syrian Revolution, speaking by telephone to a meeting in Washington.

Sayyed denied that the opposition was too divided to merit foreign support.

"It is unacceptable for the international community to claim that it is withholding its support because of the fracturing of the opposition while the Syrian people continue to be slaughtered," he told the meeting organised by the Rethink Institute.