A senior Syrian military officer has described how he defected to opposition forces after witnessing hundreds of pro-regime militiamen carry out the now infamous massacre of more than 100 civilians in the town of Houla one week ago.

The account of Major Jihad Raslan comes as the United Nations´ special envoy to Syria, Kofi Annan, yesterday warned of an increasing risk of imminent war in Syria. "The spectre of an all-out war with an alarming sectarian dimension grows by the day," Annan told an Arab League gathering.

His concerns follow warnings delivered on Friday by the United States, Britain and the UN Human Rights Council, which voted overwhelmingly to condemn the Syrian regime for the Houla killings.

The killing of so many civilians, among them 49 children and at least 20 women, continues to galvanise international anger against regime officials and their loyalist militias, which have widely been blamed for what took place.

Raslan served until last Saturday in the Syrian Air Force in the strategically vital port city of Tartous. He had been in Houla on leave when the town was shelled just after 1pm last Friday, then invaded by a civilian militia, known as the Shabiha, in the worst single atrocity of the Syrian uprising.

The officer´s account to the Observer of what took place is among the most important of the testimonies to have emerged since the massacre, the aftermath of which appears to be causing fresh turmoil inside Syria 16 months after the first stirrings of revolt inspired by the Arab spring.

Raslan said he was in his house, around 300 metres from the site of the first massacre in the village of Taldous, when several hundred men whom he knew to be Shabiha members rode into town in cars and army trucks and on motorbikes.

"A lot of them were bald and many had beards," he said. "Many wore white sports shoes and army pants. They were shouting: ´Shabiha forever, for your eyes, Assad.´ It was very obvious who they were.

"We used to be told that armed groups killed people and the Free Syria Army burned down houses," he said. "They lied to us. Now I saw what they did with my own eyes."

He said the killings in his area were over in around 15 minutes. However, the rampage in other parts of Houla continued until the early hours of Saturday, according to eye-witnesses and survivors.

"Those victims who were slaughtered are people that I knew well," Raslan said. "These children I knew well, personally. I ate with their families. I had social ties with them. The regime cannot lie about these people, who they were and what they did to them. It was a brutal act by the regime against people who were with the revolution," he said.

Raslan said that he served on a missile base in Tartous, removed from the grinding everyday savagery of Syria´s uprising. "I knew they had been lying, but I had not been exposed to the effects of it. This was the first time I had seen anything like this."

He said defections had increased sharply in the days following the massacre and he claimed to know of five defectors who were shot dead as they tried to flee through olive groves not far from Houla the day after the killings.

"Many more want to leave," he said, "but they can´t. All holidays have been cancelled by the military. It is a very serious risk if anyone tries to flee now. I was only allowed to go on leave because of exceptional family circumstances."

A second defector from Houla, a first lieutenant who was serving in nearby Homs city last weekend, said that Houla had changed the thinking of soldiers and officers like him who did not support the regime crackdown on dissent but had been too afraid to leave.

The lower ranks of the Syrian military are largely made up of Sunni Muslims, who account for around 70% of Syria´s population and who now dominate all ranks of the Free Syria Army.

Senior officers in the loyalist military are mostly drawn from the Alawite sect, which uses an uncompromising police state to maintain its iron-clad grip on Syrian society.

"There were no Sunni soldiers around Houla itself [when the massacre took place]," the former officer said. "They are all Alawites there, the officers and the soldiers. "[Houla] is a very sensitive area. Many of the Shabiha in Syria come from here. They won´t defect from here."

The officer said he had regularly seen Shabiha groups work alongside regime forces, but said they appeared to take orders from intelligence officers, particularly the Air Force Intelligence Directorate, which has played a frontline role in the regime crackdown. "The military give them weapons and cover, and escort them in tanks," he said. "But they sometimes work independently."

Few cracks have appeared among Assad´s core support base, with the upper ranks of the military remaining supportive of the crackdown, which is being portrayed by Damascus as a battle against foreign- backed Sunni jihadists who are trying to overthrow the regime.

"In other places away from Houla, it is not impossible that the Alawites might defect," the officer said. "They are starting to be worried now, starting to fear that Bashar [al-Assad] might leave.

"I want to get my two brothers to leave. It is a very sensitive, dangerous situation for my family. Everyone is at risk. From the beginning we knew that they were lying. Everything was a lie. But my family is the most important thing. We need to protect each other."

Shelling has continued on most days since the massacre and Raslan said Houla residents believed that regime forces were targeting houses where massacres had taken place. "They want to destroy the evidence," he said. "They want to kill the witnesses." (guardian.co.uk © Guardian News and Media Limited 2012 06/03/12)