Syrian activists have announced a new rebel coalition that aims to overcome deep divisions within the opposition in its fight against the forces of President Bashar Assad.

The group, the Syrian Rebels Front, declared its formation Monday in a news conference in Turkey. But it was uncertain how the new organization would co-ordinate with other sectors of the Syrian opposition, whose failure to unite has hobbled its campaign to topple Assad despite a nationwide uprising that has lasted more than one year.

Khaled al-Okla, one of the organizers, said the fledgling group will co-ordinate with the Free Syrian Army, a loose coalition of rebel units whose nominal leaders are based on the Turkish side of the border with Syria.

Members of the Free Syrian Army acknowledge its commanders have limited or no operational control over rebel units inside Syria, but they say the label has given a public face to the lightly armed factions, who are under heavy pressure from government forces with tanks and artillery.

"We might have some treaties or agreements to co-ordinate our work in Syria," said al-Okla, who claimed his umbrella group has 12,000 fighters.

Ceasefire abandoned

He also read a statement that said the Syrian Rebels Front had been formed in light of Assad's "scorched earth policy" as well as "the failure of all Arab and international initiatives to rein in Assad from his crimes," suggesting the rebels were giving up on a peace plan proposed by UN envoy Kofi Annan.

According to Reuters, a spokesperson for the Free Syrian Army announced Monday that the group is no longer bound to the UN-backed truce after Assad had ignored a Friday deadline to implement it.

"We have decided to end our commitment to this [ceasefire]," Free Syrian Army spokesman Major Sami al-Kurdi is reported to have said. "We have resumed our attacks but we are doing defensive attacks which means we are only attacking checkpoints in the cities."

The 15-month-old revolt against Assad's rule has killed up to13,000 people, according to activist groups.

In a speech on Sunday, Assad defended his government's crackdown on opponents and insisted the revolt was the work of foreign-backed extremists, not reformers seeking change.

Assad was responding to international condemnation of the massacre of more than 100 people, including dozens of children, in the town of Houla. Syrian forces have been blamed for the killings.

Arming rebels

While some Gulf countries support the idea of arming rebels, Western and Arab allies have been reluctant to supply anti-regime fighters, partly because of their lack of cohesion, and also for fear of igniting a broader and more intense conflict.

Turkey has said it is not providing military aid to Syrian rebels, but it allows opposition groups to organize on its soil and also gives medical and other humanitarian aid to thousands of Syrian refugees, as well as hundreds of army defectors, who have fled their country. Turkey has said it would consider establishing a buffer zone inside Syria if border security deteriorates, though such an outcome does not appear imminent.

With files from CBC