Syria may have accepted a UN peace plan, but bloodshed continued Tuesday with violent clashes between government troops and rebels near the country's border with Lebanon.

A spokesperson for Kofi Annan, the joint UN and Arab League envoy, said Annan had received a letter from the Syrian government agreeing to the conditions of his six-point peace plan, which includes a daily two-hour break in fighting to accommodate the delivery of humanitarian assistance and an eventual army ceasefire.

But the plan was met with skepticism, with critics accusing President Bashar Assad of agreeing to a ceasefire just to buy time for his troops to recharge.

"We are not sure if it's political maneuvering or a sincere act," Louay Safi, a member of the opposition Syrian National Council, told the Associated Press. "We have no trust in the current regime. ... We have to see that they have stopped killing civilians."

Syrian democracy activist Rami Jarah was more blunt in his assessment.

"The Syrian government is going to depend on propaganda as it has over the past few months -- propaganda of armed terrorists," Jarah said in Istanbul, Turkey.

The year-long uprising against Assad's regime has now claimed more than 9,000 lives, the UN said.

Annan's plan also seeks the speedy release of arbitrarily detained prisoners; freedom of access for journalists; freedom of protest and assembly for Syrians; and Syria-led talks aimed at brokering a political solution.

But the plan's acceptance did not see an immediate end to the violence, as there were more reports Tuesday of intense clashes between Syrian troops and rebel fighters near Lebanon.

Lebanese security officials reported gunfire spilling across the border. There were conflicting reports about whether Syrian troops physically entered Lebanese territory.

Speaking to reporters in Washington, U.S. Secretary of State Hillary Rodham Clinton said Assad must act immediately to stop the bloodshed.

"We will judge Assad's sincerity and seriousness by what he does, not by what he says," she said. "If he is ready to bring this dark chapter in Syria's history to a close, he could prove it by immediately ordering regime forces to stop firing and begin withdrawing from populated areas."

Annan said he had received the backing of both Chinese and Syrian officials for his peace plan.

Working on behalf of the UN and Arab League, Annan travelled to Syria and met with both Assad and opposition leaders in early March. He came away from that trip without any agreements, however, and has since been exerting pressure on Russia and China. As Syria's last significant allies on the world stage, both have been using their sway at the United Nations to shield Syrian leader Bashar Assad's regime from sanctions or intervention.

The tide turned last week, when both Russia and China backed a non-binding statement that stopped short of calling for "further measures" in the event Assad's regime does not ease its crackdown on protesters.

After meeting with Chinese Premier Wen Jiabao in Beijing, Annan told reporters he is now hoping to work with Syria to translate his plan into action.

"So we will need to see how we move ahead and implement this agreement that they have accepted," he said.

According to Annan's peace plan the UN should expect regular and timely updates on the pace of its implementation on the ground in Syria.

"In the light of these reports, the Security Council will consider further steps as appropriate," the plan states.

In Syria, Assad visited the former rebel stronghold of Baba Amr in the city of Homs Tuesday. The tour comes less than a month after Assad's forces overran the neighbourhood following a weeks-long siege that left hundreds dead, many of them civilians.

Although Assad was shown on Syrian state TV vowing to restore Baba Amr "better than it was before", the state-run SANA news agency reported few other details of his visit.

The Syrian uprising began with mostly peaceful protests against Assad's regime last March. Soon after, government forces launched a violent crackdown that saw tanks and armed soldiers dispatched to break up protests.

In turn, rebel forces escalated their response as they took up their own arms.

As the violence has intensified and diplomatic efforts have repeatedly failed in recent months, concern that the country is spiralling into civil war has increased.

With the lack of a united opposition front contributing to that concern, the opposition summit in Turkey on Tuesday is aimed at reaching a consensus ahead of another meeting there on April 1.

Representatives from the United States, as well as Europe and the Arab nations are all due to attend.