DAMASCUS: President Bashar al-Assad said his future could only be decided at the ballot box and denied Syria was in a state of civil war, despite fresh attacks and heavy fighting on Friday near the Turkish border.

As the opposition met for crucial unity talks in Qatar, the United Nations underlined the humanitarian crisis by saying more than 11,000 Syrians had fled into neighbouring countries in the past 24 hours alone.

The UN also said it expected the number of people inside Syria in need of emergency humanitarian aid to rise to more than four million early next year.

In an interview with Russian television, Assad said that whether the president can “stay or leave” is a “popular issue” and “the only way (it) can be done (is) through the ballot boxes.”

Assad warned that Syria was facing a protracted conflict because foreign powers were backing rebels fighting his regime, but insisted there was no civil war.

He admitted divisions existed in the country, but said “division does not mean civil war,” and denied his forces had committed war crimes.

State-backed Russia Today (RT) had on Thursday released excerpts of the interview in which Assad vowed to “live in Syria and die in Syria” and warned that foreign intervention in his country would have global consequences.

Assad's comments came as clashes continued and activists staged traditional Friday protests against his regime.

Some of the heaviest fighting saw at least 20 Syrian soldiers killed over the Ras al-Ain border post, one of only two crossings on the Turkish border still in regime hands, the Syrian Observatory for Human Rights said.

Fighting over the post left at least 16 Syrian soldiers and 10 rebels dead on Thursday, the Observatory said, and forced thousands to flee.

Panos Moumtzis, the regional coordinator for the UN's refugee agency, said in Geneva that 9,000 people had fled to Turkey and 1,000 each to Jordan and Lebanon in the previous 24 hours, bringing to more than 408,000 the number of registered Syrian refugees in the region.

A car bomb outside a mayor's office in the town of Muadamiya al-Sham south of Damascus killed four civilians on Friday, the Observatory said, while at least 12 civilians were killed in shelling in the eastern province of Deir Ezzor.

An AFP correspondent in Damascus said warplanes flew over the city and heavy explosions were heard in the early morning and late afternoon.

On Thursday, 142 people were killed nationwide, including 56 civilians, said the Britain-based Observatory, which relies on a network of activists and medics on the ground.