A spokesman for international peace envoy Kofi Annan has said the international community must ensure that the peace plan for Syria is implemented by both sides.

However, Ahmad Fawzi said that Mr Annan did not favour expanding the ceasefire monitoring mission at this time.

Mr Annan is to brief the United Nations Security Council and General Assembly on Thursday.

Mr Fawzi said that in time the international community would have to review the crisis in Syria and decide what needed to be done to implement the UN/Arab League backed peace plan.

Earlier, dozens of soldiers were been killed in battles between Syrian government forces and armed rebels, a watchdog reported.

This comes as the EU and Russia aim today to work together to end the 15-month-old crisis in Syria.

Major Sami al-Kurdi, a spokesman for the rebel military council said rebels wanted a UN observing mission in the country to be turned to a "peace enforcing mission" or the international community should take "bold" decisions and impose a no-fly zone and a buffer zone.

President Bashar al-Assad has vowed to crush an anti-regime uprising and the rebel Free Syrian Army announced on Friday that it was resuming "defensive operations."

The Syrian Observatory for Human Rights said 19 soldiers, eight rebels and 19 civilians were killed in violence across the country on Sunday.

On Saturday, another 89 people were killed, including 57 soldiers, the largest number of casualties the military has suffered in a single day since the uprising broke out in mid-March 2011, the watchdog said.

Fresh clashes erupted in Idlib province late on Sunday, killing two opposition fighters, as explosions were reported in Damascus province, the Observatory said.

The exiled opposition Syrian National Council reported violence across Idlib today, saying regime forces were using "tanks, rocket launchers and artillery" to bombard several parts of the province.

Reports from Syria cannot be independently verified as state authorities have barred international journalists and rights groups.

At the EU-Russia summit in Saint Petersburg, the bloc's President Herman Van Rompuy said Moscow and Brussels must work together to end the crisis, adding that they agreed the Annan peace plan was the best way to avoid civil war.

The crisis in Syria, with Russia blocking Western efforts to condemn President Assad and force him from power, is expected to overshadow talks on trade and other issues at the twice-yearly summit.

EU nations have called for Russia to press the Syrian leader to withdraw weaponry and halt attacks as demanded by the plan, and want him to step aside to make way for a political transition.

Russia says it is not protecting Mr Assad, but that the Syrian leader's exit cannot be a precondition for political dialogue.

Mr Putin ceded no ground in remarks during visits to Berlin and Paris on Friday, stressing rebel violence, criticising sanctions and saying political decisions could not be forced on Syria from outside.

EU foreign policy chief Catherine Ashton, who met Russian Foreign Minister Sergei Lavrov yesterday, said in a statement: "Russia's role is crucial for the success of Annan's plan."

She said the EU wanted to "work closely with Russia to find a way to end the violence and support" the plan.

The statement said she spoke to Mr Annan by phone yesterday and that they agreed the crisis had reached a "critical point".