Syrian government forces continued to attack opposition fighters Tuesday, breaking the terms of a United Nations brokered ceasefire and ending what may be the final chance for a diplomatic conclusion to the year-long conflict.

Despite reports of fighting in at least two towns, President Bashar al-Assad's government claimed military forces had begun pulling out of some areas in compliance with the ceasefire agreement to withdraw forces from towns and villages by Tuesday.

All hostilities were set to end by 6 a.m. Thursday morning.

The failure of the ceasefire, brokered by U.N.-Arab League peace envoy Kofi Annan after weeks of desperate shuttle diplomacy, is a bitter blow for the international community, who now fear the conflict will escalate into all out civil war.

We have already withdrawn forces and army units from several Syrian provinces, Syrian Foreign Minister Walid Moallem claimed in Moscow after talks with his Russian counterpart, according to the AP.

The failure comes after Syrian forces fired across the border into a Turkish refugee camp, killing at least two and wounding several others.

Turkish Prime Minister Recep Tayyip Erdogan responded by saying his country is considering what steps to take in response, including measures we don't want to think about.

Turkey has previously floated the idea of creating security zones along its borders to protect the 24,000 Syrian refugees, who have already fled there, a move which would drag the Turkish military into the conflict.

Also on Monday, Syrian government forces killed a TV journalist across the border in Lebanon.

Both acts highlight the risk of the fighting spilling across borders, escalating the battle between opposition forces and the Damascus regime into a regional conflict.

According to the Syrian Observatory for Human Rights, an aid group with monitors on the ground in Syria, regime troops fired shells at the town of Mariah in northwestern Syria on Tuesday. Activists also said the central city of Homs was struck by mortar rounds