DAMASCUS, Mar 29, 2012 (AFP) - Syrian forces assailed rebel bastions on Thursday as Arab leaders gathered in Baghdad for a landmark summit focussed on ending the year-long violence.

On the eve of the meeting, the United States accused Syria's President Bashar al-Assad of failing to respect a peace plan that UN Secretary General Ban Ki-moon said his regime had accepted.

The United Nations estimates that more than 9,000 people have been killed in the Assad regime's crackdown on an uprising that began with democracy protests in March 2011.

Arab leaders meeting in the Iraqi capital are expected to stop short of calling for Assad to quit -- as advocated by Qatar, Saudi Arabia and much of the West -- to resolve the crisis.

As the diplomatic gears turned, Syrian security forces launched a new onslaught after Damascus had made it clear it would not abide by any of the Arab summit's initiatives.

Violence across Syria killed at least five people, including three civilians, early on Thursday, said the Syrian Observatory for Human Rights monitoring group.

The civilians died as regime forces stormed villages near the town of Maaret al-Numan, in northwestern Idlib province, which has been under a relentless army assault since the start of the month, said the Observatory.

In central Hama province, two soldiers were killed when armed rebels attacked their vehicle, while clashes were also taking place near the town of Zabadani, in Damascus province.

A loud blast was reported in Harasta, also in Damascus province, and plumes of smoke could be seen rising near an army checkpoint, said the Britain-based group.

Fierce clashes were taking place between regime forces and rebel in the village of Dael, in the southern province of Daraa, cradle of the popular uprising.

The violence was taking place despite the United Nations saying earlier this week that Assad had agreed to a six-point plan drawn up by UN-Arab peace envoy Kofi Annan.

The regime has ignored a chorus of international condemnation and pressed on with its campaign to crush strongholds of rebel fighters, who outgunned and outnumbered, have resorted to hit-and-run tactics.

Ahead of the gathering in Baghdad, the United States accused Assad of failing to respect Annan's plan, which includes a commitment to stop all violence, daily two-hour humanitarian ceasefires and media access to all areas affected by the fighting.

It also calls for an inclusive Syrian-led political process, the right to demonstrate, and the release of people detained arbitrarily.

"Assad has not taken the necessary steps to implement" the peace plan crafted by former UN secretary general Kofi Annan, said State Department spokeswoman Victoria Nuland.

"Washington is concerned over "arrests and violence continuing in Syria today," Nuland told reporters, vowing to "keep the pressure on Assad."

"We will judge him on his actions, not his promises," she added, echoing comments made Tuesday by Secretary of State Hillary Clinton.

In Baghdad, Iraqi Foreign Minister Hoshyar Zebari said Wednesday that Arab nations at the summit would stop short of calling for Assad to quit or discuss arming his foes.

But Syrian foreign ministry spokesman Jihad Makdissi said that in any case Damascus would pay no heed.

"Syria will not cooperate with any Arab League initiative at any level," he said.

The 22-member pan-Arab body in November voted at an extraordinary meeting to suspend Syria until Assad implemented an Arab deal to end the bloodshed.

Meanwhile, the BRICS group of powerful emerging market nations agreed Thursday that only dialogue can resolve violence in Syria and the crisis over Iran's nuclear ambitions, Indian Premier Manmohan Singh said.

"We agreed that a lasting solution in Syria and Iran can only be found through dialogue," Singh said in a closing statement at the summit in New Delhi attended by the leaders of Brazil, Russia, India, China and South Africa.

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