At least 14 people were killed in violence in Syria on Friday, most of them civilians in the restive city of Homs, as Human Rights Watch accused the regime of crimes against humanity.

The Arab League, meanwhile, held a preparatory session in Cairo on the eve of a meeting of foreign ministers to discuss Syria's failure to respect proposals to end the crisis.

Opposition leaders have been pressing the League to suspend Syria's membership over the crisis which the UN says has cost more than 3,500 lives since protests against President Bashar al-Assad erupted in mid-March.

Eight people were killed in Homs in the latest violence, including four civilians shot by security forces in Al-Bayada neighbourhood and a 63-year-old man shot by a sniper, the Syrian Observatory for Human Rights said.

Residents in Homs also found the corpse of a young man who went missing the previous day and the bodies of two others, the Observatory said, without saying when they were killed.

The deaths in Homs came amid mass anti-regime rallies demanding the Arab League suspend Syria's membership in the pan-Arab body to sanction its brutal, eight-month crackdown on dissent.

Security forces broke up demonstrations in Al-Malaab, a main thoroughfare in Homs, but rallies relocated and mushroomed, engulfing eight neighbourhoods, the Observatory said.

Five people died in Daraa province, cradle of the revolt, including a 13-year-old boy killed by a bomb blast in Mseifra and a man hit by security forces who opened fire against protesters in the same town.

In the northwestern province of Idlib, near Turkey, "security forces shot dead a man in the town of Ariha," where demonstrations erupted after the weekly Muslim midday prayers.

The Observatory also reported the entry of tanks into the Idlib town of Sheikhun in the wake of "mass demonstrations" and "violent clashes" that led to the "retreat by security forces from government buildings."

In Damascus, security forces on the streets of Barzeh and posted snipers on rooftops, after a wave of arrests and deadly violence shook the neighbourhood.

And "security forces unleashed heavy gunfire to disperse demonstrations," in the eastern oil hub of Deir Ezzor.

Friday prayers have become a lightning rod for demonstrations in Syria, which each week adopt a new theme and this week called for the Arab League to suspend Syria's membership.

The League, under international pressure to act after Syria failed to honour a peace deal and instead stepped up its brutal protest crackdown, held talks ahead of a meeting on Saturday to discuss the crisis.

Syria's envoy to the Arab League, Yussef Ahmad, presented a memorandum in which Damascus expressed its willingness to receive a pan-Arab delegation.

"This will help assess Damascus's commitment to the (Arab) plan and to unveil motives behind certain external and internal parties working for the failure of the Arab blueprint," the official SANA news agency said.

Meanwhile, Human Rights Watch (HRW), like protesters, urged the Arab League to suspend Syria's membership.

It accused Syrian government forces of "crimes against humanity" based on the systematic nature of abuses against civilians.

It said protesters were unarmed in most clashes, but that defectors from the security forces had intervened when the demonstrators came under fire from regime troops and militiamen.

Based on the accounts of 110 victims and witnesses, HRW said "violations by the Syrian security forces killed at least 587 civilians" in Homs and its province between mid-April and the end of August.

In their latest assault on the flashpoint city, at least another 104 people have been killed since November 2 when the regime agreed to the Arab League initiative to end the violence.

"Homs is a microcosm of the Syrian government’s brutality," said Sarah Leah Whitson, HRW's Middle East director.

"The Arab League needs to tell President Assad that violating their agreement has consequences, and that it now supports Security Council action to end the carnage," she said.

Under the deal, Damascus was to release those detained for protesting and withdraw military forces from towns and cities. It says it has already released more than 500 people.

Elsewhere, a Lebanese man's leg was blown off after he stepped on a mine planted hours earlier by Syrian troops along Lebanon's northern border, local and hospital officials said.

And strapped for cash after sanctions imposed by the European Union, Syria has stopped paying Shell and Total for their oil production in the country, the Financial Times reported.