President Hollande and British PM Cameron agree to step-up pressure on Syria's al-Assad

French President François Hollande and British Prime Minister David Cameron say they will work together to increase pressure on the regime of Syrian President Bashar al-Assad. 

Reuters/Christophe Ena/Pool

Hollande’s office also announced that France will host a Friends of Syria meeting in Paris and issued a statement condemning the Damascus regime's use of artillery in a massacre that killed at least 108 people on Friday and Saturday.

The president's office said the country's leaders would have to answer for their "murderous folly"

Meanwhile, violence continued across Syria on Monday when 25 people were reportedly killed in clashes in a number of restive provinces.

The Syrian Observatory for Human Rights said clashes raged in several provinces Monday, including Idlib in the northwest and Daraa in the south, where the uprising against the regime first erupted more than 14 months ago.

Three civilians were among those killed on Monday, including a 14-year-old boy who was shot dead by a sniper in Al-Faria neighbourhood of the central city of Hama, the Britain-based Observatory said.

The violence continued as UN-Arab League envoy Kofi Annan arrived in Damascus to try and salvage a battered ceasefire.

More than 280 unarmed military observers are in Syria to monitor a cessation of hostilities that started officially on 12 April but lurches closer to collapse each day.

More than 13,000 people have been killed in Syria since an anti-regime revolt broke out in March 2011, according to the Observatory.