Syria has accepted a UN-sponsored peace plan, international envoy Kofi Annan said on Tuesday, as troops loyal to President Bashar Assad raided rebel forces who have taken refuge across the border in Lebanon.Syrian troops advanced into north Lebanon, destroying farm buildings in pursuit of Syrian rebels, residents said. Lebanese security sources denied that the Syrian troops had stepped onto Lebanese territory.“A peaceful transition means that the regime needs to be changed. And that starts with the removal of the head of the state,” spokeswoman Basma Kodmani said.Shifting from its initial unqualified backing of Damascus, Russia has given Annan’s proposal its full backing and said it could be Assad’s “last chance” to avoid a protracted and bloody civil war.The opposition has rejected Assad’s calls for dialogue saying it is too late. The crackdown has angered Arab countries including former allies Qatar and Saudi Arabia, which favor arming the rebels.But Arab leaders due to meet in Baghdad on Thursday will support a Syrian-led transfer of power, Iraq’s foreign minister Hoshiyar Zebari said on Monday.“There has to be a political solution, fundamental constitutional and political changes for transfer of power in Syria but through a Syrian-led process,” Zebari said. “We are not in a position to dictate to the Syrians what of kind of president, what kind of leader they should have.”The border is poorly marked. Incursions have been reported in the past months without triggering Lebanese protests.Assad made a rare foray into the heartland of Syria’s yearold uprising, visiting a rebel stronghold in the city of Homs that his forces had overrun after weeks of shelling and gunfire, apparently to make the point that he can tour the streets of the bitterly fought-over district.Syrian state television showed video of Assad, wearing an open-necked shirt with a blue suit, walking casually in the devastated streets of the Baba Amr district and talking to groups of supporters and troops in combat gear.Baba Amr was an emblem of opposition and rebel army defiance until it was reclaimed by government forces early this month after 26 days of heavy bombardment that opposition activists said was indiscriminate.“Life will return to normal in Baba Amr, better than it was before,” Assad said.Al Jazeera reported shots had been fired at Assad’s convoy in Homs, but those reports could not be independently confirmed.Activists says hundreds of civilians and opponents of Assad were killed in Baba Amr in February by shelling and snipers.“He thinks he won and scored a great victory,” said opposition activist Saif Hurria, speaking by telephone from Homs. “He wants to show the world he defeated and put down a revolution. But... it seems he can’t even release the video until he has left Homs. That is not control” Opposition supporter Abu Jaafar said Assad’s appearance in Homs was “giving the green light to kill like this again.”Annan represents the UN and the Arab League. Through a spokesman he said Assad had accepted the basic terms of a peace plan that calls for national dialogue but does not hinge on him leaving office.Western and Arab leaders are due to meet in Istanbul on Sunday to discuss a political transition, and the Arab League and Turkey were pressing various wings of the Syrian opposition to unite.In a session on Monday, the People’s Assembly of Syria called on Assad to postpone parliamentary elections set for May 7 to allow time for the consolidation of comprehensive reforms and the outcome of a national dialogue.Annan had said on Monday that Assad’s government could not resist the “winds of transformation,” but it was too early to introduce any timeline for a peaceful solution.He said Assad’s acceptance of the peace plan was “an important initial step” but conceded he faced a “long and difficult task” in ending the fighting and said he could not set any timetable.Annan’s plan calls for withdrawal of heavy weapons and troops from population centers, humanitarian assistance being allowed in unimpeded, release of prisoners, freedom of movement and access for journalists to go in and out, Annan said.Opposition activists reported several civilian casualties in shooting late on Monday and overnight in the cities of Idlib and Homs, in fighting between government forces and rebels.Video posted on the Internet by activists showed thick black smoke and blazing buildings in a district of Homs. There were wounded and bleeding men and women lying in a street.Security appears to be fraying in many parts of Syria despite repeated army offensives to regain rebellious territory. Activists say the government is struggling to hold such areas for long, with rebels swiftly reemerging, as they have in other parts of Homs.In Turkey, Syrian rebel group leaders gathered to weigh how to unite their fractured movement and boost foreign backing for the revolt.The main opposition block voiced support for Annan’s plan – so long as it led to Assad’s removal.