Most of the 108 people killed in the Syrian town of Houla were civilians and entire families were shot in their homes, the UN human rights office said on Tuesday.

Witnesses and survivors have told UN investigators that most victims died in two bouts of summary executions carried out by pro-government 'shabbiha' militiamen in the nearby village of Taldaou last Friday, UN rights spokesman Rupert Colville said.

'It is believed at this point, and I would stress we are at very preliminary stages, that under 20 of the 108 can be attributed to artillery and tank fire,' he added. 'What is very clear is that this was an absolutely abominable event that took place in Houla, and at least a substantial part of it were summary executions of civilians - women and children,' he said.

'At this point it looks like entire families were shot in their houses,' he said. Some 49 children and 34 women were among the known victims, but the toll was not definitive, Colville said, adding: 'There are reports of more deaths.'     

'Almost half of the ones we know of so far are children - that is totally unpardonable - and a very large number of women as well,' Colville said.

Some witnesses indicated that the Shabbiha came from the surrounding area, but more investigation is required, Colville said. The information came from UN investigators at the site as well as other sources whom he declined to identify.

The Syrian government has blamed Islamist militants for the killings in Houla.

Initially, when UN investigators reported a total of 85 bodies photographed in a morgue on Saturday, they included 32 children under the age of 10, according to Colville. He did not know the ages of all 49 children now known to have been killed.

Separate UN rights investigators led by Brazilian expert Paulo Pinheiro, had said in a report, covering the period since March and issued just days before the Houla killings, that government forces executed entire families in their homes - often entering a town with a list of wanted.

That report, based on more than 200 interviews, also said that rebels had tortured and killed soldiers and government supporters.     
President Bashar Al-Assad met peace envoy Kofi Annan on Tuesday amid an growing international outcry over the massacre, which the government on Monday blamed on Islamist militants.

Syria has never allowed the UN-backed commission of inquiry led by Pinheiro into the country to investigate.
 Colville urged the government on Tuesday to grant them 'immediate and unfettered access to the country'.

'It is extremely important that we get to the bottom of exactly what happened,' he said. 'When you have this kind of crime, ideally you would have forensic investigations. In current circumstances it's obviously not going to be that easy'.     

UN High Commissioner for Human Rights Navi Pillay on Sunday called for a full investigation and urged the Security Council to refer the situation in Syria to the prosecutor of the International Criminal Court (ICC).

'It's been said time and time again that these are very serious international crimes. This is the latest and one of the worst examples,' Colville said. 'It has been pretty well established by the Commission of Inquiry, by the High Commissioner herself and by many other sources that at the very least crimes against humanity have taken place in Syria.' - Reuters