Al Qaeda head Ayman al-Zawahiri threw his support behind rebels in Syria as the country's Arab neighbours cut it adrift and vowed to support the uprising against president Bashar al-Assad.

Arab League ministers meeting in Cairo called for a joint Arab and United Nations peacekeeping mission in the troubled country and vowed political and material support for the rebels.

The call came as regime troops continued their deadly assault on areas of the flashpoint city of Homs.

Speaking in a video message, al-Zawahiri described the Assad government as a "cancerous regime" that was suffocating the people of Syria.

He called on Muslims to offer whatever help they could, urging them not to rely on the West or the Arab League.

A US media report citing unnamed American officials said Al Qaeda's Iraqi branch was likely to have carried out twin bombings in the northern city of Aleppo on Friday, in which authorities said 28 people were killed.

The report also said Al Qaeda was behind attacks in Damascus in December and January.

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Iraq's deputy interior minister, Adnan al-Assadi, said Baghdad had "intelligence information that a number of Iraqi jihadists went to Syria" and that "weapons smuggling is still ongoing".

In Cairo, Arab League foreign ministers issued a strongly worded resolution saying the Syrian government had violated international law and the perpetrators deserved punishment.

The resolution called on Arab member states to impose economic sanctions and end diplomatic contact with the Assad regime.

It also called on the UN Security Council to form a joint Arab-UN peacekeeping force, and for the opening of communication channels with the Syrian opposition to provide it with political and material support.

Individual ministers vowed to increase pressure on Russia and China to lift their veto on intervention.

Syria immediately rejected the latest resolution.

Al Qaeda blamed: The site of Friday's attacks in Aleppo ( Reuters: SANA )

The country frequently blames foreign-backed "armed terrorist gangs" for the violence.

In the latest violence in Syria, the Syrian Observatory for Human Rights reported that 14 people were killed in a relentless assault by Mr Assad's forces in Homs.

All but one of them died in the suburb of Baba Amr, a rebel stronghold which armed forces have targeted for more than a week, killing at least 500 people, according to activists.

The Observatory also reported fierce clashes on the northern edge of nearby Rastan, where a woman was killed when a rocket hit her home.

Elsewhere, snipers killed a child in Daraa.

Meanwhile, Syrian state media said brigadier general and doctor Issa al-Khawli had been assassinated outside his Damascus home.

As the military pressed its onslaught on Homs, refugees who fled from the city to Lebanon recounted the horrors they had witnessed.

"The army of Bashar al-Assad destroyed our homes," Abu Ibrahim said.

"Before, we were bombarded by mortars or rocket-propelled grenades, but now they are using tanks and helicopters."

Mr Ibrahim said that his 10-year-old daughter Nada has refused food since seeing dead bodies littering the streets of the besieged city.

Rights groups say more than 6,000 people have died since protests began in Syria in March last year, inspired by similar movements in Tunisia, Egypt and Libya.

ABC/wires