Syria's leaders will have to answer for their "murderous folly", the French president's office said Monday, a day after the UN Security Council condemned the slaughter of civilians there.
"The Houla massacre and the events of the these last days in Syria and in Lebanon illustrate, once more, the danger of Bashar al-Assad's regime's actions for the Syrian people," said a statement.
"The murderous folly of the Damascus regime represents a threat for regional security and its leaders will have to answer for their acts," it added.
The statement came a day after French President Francois Hollande and British Prime Minister David Cameron discussed the crisis by telephone.
"In the face of such a situation and the Damascus regime's unacceptable contempt for the ceasefire," Hollande and Cameron had agreed to look at ways to work together to increase international pressure on Assad "and to put an end to the bloody repression against the Syrian people, who aspire to freedom and democracy."
France will host a Friends of Syria meeting in Paris, the statement said.
And Hollande will discuss Syria with Russian President Vladimir Putin when he visits Paris on Friday, it added.
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Russia signed up to Sunday's UN Security Council resolution, but it has been condemned for having previously vetoed two rounds of sanctions against Assad's regime. It continues to supply arms to its Soviet-era ally.
On Sunday, the UN Security Council strongly condemned the Syrian government for using tanks and artillery in the massacre at Houla, central Syria. Of those killed, 49 were children.
Syria has denied any responsibility and said it will launch an investigation into the carnage that took place on Friday and Saturday.
US Secretary of State Hillary Clinton on Friday expressed concern that the unrest in Syria is "contributing to instability" in neighbouring Lebanon.
Armed clashes between supporters and opponents of Assad's regime have taken place in recent weeks in both the northern Lebanese city of Tripoli and the capital Beirut.
The statement from the French president's office did not say when the Friends of Syria meeting would take place. It would be the third such gathering after one in Tunis in February and another the following month in Istanbul called for tougher action against the Assad regime.
The United States, France, Britain, Germany, and Arab nations Saudi Arabia and Qatar are leading members of the Friends.
On Saturday, the rebel Free Syrian Army called for the Friends of Syria to carry out air strikes on forces loyal to Assad, as reports of the Houla massacre emerged.