The French government has urged military action against the Syrian regime as the year-long crackdown against reformists continue despite the UN-brokered ceasefire.
"[The UN has] to move on to another step which we have already started raising with our partners, under Chapter Seven of the United Nations charter," French foreign minister Alain Juppe told Sky News.
Chapter Seven suggests military action can be authorised by the UN Security Council if peace is threatened by an act of aggression in the region.
Juppe said the ceasefire had been compromised and that the UN's decision to send 300 monitors into the country should be done within a fortnight - not the three months proposed.
Since the ceasefire came into effect on 12 April, more than 300 civilians have been killed across the region, according to reports.
On Wednesday, four civilians were killed on a bus during a clash with Syrian forces, anti-government activists said. Activist groups said there were more outbreaks of violence across the region and a much higher death toll.
"Either this mediation is working or it isn't. If it doesn't work, we cannot continue to allow ourselves to be challenged by the regime in place, which has not adhered to the six points of the Kofi Annan plan. We have to move into a new phase," Juppe said, according to Euronews.
After a meeting with Syrian opposition members, Juppe said he had hoped Syrian ally Russia would draw the right conclusions from Syria's efforts to block the monitors' deployment.
Amid growing scepticism among Western leaders, a senior diplomat expressed his outrage against the regime for not complying with the peace plan.
"Everything we have seen suggests that the Syrians want to play for time and they haven't any real intention to start a political process and a transition. But we need to call their bluff, as it were, and test that," the unnamed diplomat was quoted as saying in Reuters.
Earlier, UN and the Arab League special envoy Annan urged the UN to speed up the process of sending more monitors to resolve the situation in Syria.