Syria’s civil war spilled over into neighboring Lebanon once again on Sunday, with gun battles in the northern city of Tripoli between supporters and opponents of President Bashar Assad’s regime that left four dead.

Nine Syrian judges and prosecutors also defected to the opposition. It was the latest setback for the regime, which appears increasingly embattled with rebels making gains in northern Syria and near Damascus, the capital.

Germany’s Federal Intelligence Service chief Gerhard Schindler predicted the Assad regime would not survive.

“Signs are increasing that the regime in Damascus is in its final phase,” he was quoted as telling the daily Frankfurter Allgemeine Sonntagszeitung.

In Geneva, the United Nation’s Special Representative for Syria and the Arab League, Lakdhar Brahimi, met with Russian Deputy Foreign Minister Mikhail Bogdanov and U.S. Deputy Secretary of State William Burns to discuss the crisis in Syria. They said in a joint statement that the situation in Syria was “bad and getting worse,” adding that a political process to end the conflict was “still necessary and still possible.”

Russia and the United States have argued bitterly over how to address the conflict, which began with peaceful protests against Assad in March 2011 and escalated into a civil war that has killed an estimated 40,000 people. Activists said another 45 were killed on Sunday.

The U.S. has criticized Russia for shielding the Assad regime, while Moscow has accused Washington of encouraging the rebels and being intent on regime change.

In Moscow, Russian Foreign Minister Sergey Lavrov said that Russia agreed to take part in the Geneva talks on condition there would be no demand for Assad to step down. Washington and its allies, including Turkey, have repeatedly called on the Syrian president to leave power to help stop the bloodshed.

“We are not conducting any negotiations on the fate of Assad,” Lavrov said, adding that the Americans were wrong to see Moscow as softening its position on Syria. “All attempts to portray things differently are unscrupulous, even for diplomats of those countries which are known to try to distort the facts in their favor.”

Addressing fears that Assad could use chemical weapons in a last-ditch effort to save his regime, Lavrov once again said the Syrian government has given assurances that it has no intention of ever using the weapons of mass destruction. He said the greatest threat is that they would fall into the hands of militants.

Lavrov met last week with Brahimi and U.S. Secretary of State Hillary Rodham Clinton in Dublin. Afterward, Clinton said the United States and Russia were committed to trying again to get both sides in the Syrian conflict to talk about a political transition. Clinton stressed that the U.S. would continue to insist that Assad’s departure be a key part of that transition.

Russia’s foreign minister said that after he agreed to a U.S. proposal to have his and Clinton’s deputies “brainstorm” on Syria, the Americans began to suggest that Russia was softening its position.

“No such thing,” Lavrov said. “We have not changed our position.”

He urged the international community to come together and “with one voice” to demand a cease-fire, return U.N. observers in bigger numbers and begin a political dialogue. Lavrov repeated that Russia was not wedded to Assad but believed that only the Syrians have the right to choose their leaders.

In Lebanon, fighting between pro-and anti-Assad gunmen flared as bodies of three Lebanese, who were killed after crossing into Syria to fight in the civil war were brought back home for burial, the state-run National News Agency said.

Four people were killed and 12 were wounded in the gunfights, the agency said. Two Lebanese soldiers were also injured, the Lebanese Armed Forces command said.

Syria civil war has often spilled into neighboring countries including Turkey, Lebanon and Israel, raising concerns of a wider war in the volatile region.

Lebanon, which Syria dominated for decades, is particularly vulnerable to getting sucked into the crisis. The two countries share a porous border and a complex web of political and sectarian ties.

Syria’s opposition is dominated by members of the Sunni Muslim minority. Assad’s regime is predominantly Alawite, an offshoot of Shiite Islam.

Tripoli has been the scene of frequent sectarian clashes between the Alawite and Sunni Muslim communities. Last week, the Lebanese army sent additional troops to Tripoli to try to prevent clashes that broke out over reports that 17 Lebanese men were killed after entering Syria to fight alongside the rebels.

In Syria, fighting between opposition fighters and regime troops was concentrated in northern Idlib province, in the Damascus suburbs and in Aleppo, Syria’s largest city, according to the Britain-based opposition activist group Syrian Observatory for Human Rights. At least 45 people were killed in fighting Sunday, said the group, which relies on reports from activists on the ground.

The defecting judges posted a joint statement online urging others to join them and break ranks with Assad’s regime. There have been a series of high-level defections over the past year, including Assad’s former prime minister. The Observatory said the latest defectors came from the northern city of Idlib.

• Barbara Surk, Associated Press