Syrian President Bashar al-Assad has said in a newspaper interview that he will not step down before elections and that the US has no right to interfere in his country's politics.

Mr Assad's comments to the Argentine newspaper Clarin raise new doubts about a US-Russian effort to get him and his opponents to negotiate an end to the country's civil war.

The comments were the first about his political future since the US and Russia agreed earlier this month to try to bring the Syrian government and the opposition to an international conference for talks about a peaceful resolution to the conflict.

The US and Russia have backed opposite sides in the conflict, but appear to have found common ground in the diplomatic push.

They envision holding the meeting next month, but no date has been set.

Neither Mr Assad nor the Syrian National Coalition, the main Western-backed coalition group, has made a firm commitment to attend.

In the interview, Mr Assad seemed to play down the importance of such a conference, saying a decision on Syria's future is up to the Syrian people and that the US has no right to interfere.

He also said a decision on his political future must be made in elections and not during such a conference.

"Any decisions having to do with reform in Syria or any political doing is a local Syrian decision," he said.

"Neither the US nor any other state is allowed to intervene in it. This issue is dealt with in Syria.

"That's why this possibility is determined by the Syrian people themselves; you go to the elections, and if you are a candidate, there are two possibilities; either you win, or you'll lose.

"These are the possibilities. You don't go to a conference to decide on an issue that has not been determined by the people."

Many in the political opposition say the Syrian president and his inner circle cannot be expected to negotiate in good faith after they brutally suppressed peaceful protests.

In the interview, Mr Assad compared himself to the skipper of a ship riding Syria's turbulent seas, saying "the country is in a crisis and when a ship faces a storm, the captain does not flee".

"The first thing he does is face the storm and guide the ship back to safety," Mr Assad said.

"I am not someone who flees from my responsibilities."

Meanwhile, reports suggest that at least 32 people have died in heavy bombardments in the city of Al-Qusseir, 10km from the Lebanese border.

The long-standing stronghold for rebel fighters has allegedly been surrounded by government troops.

Lebanese Hizbollah militants are believed to have attacked the town alongside Syrian troops.