PARIS: The Syrian opposition appealed Monday for hundreds of millions of dollars (euros) to step up the revolt against Bashar al-Assad, as the president asserted his forces had made "significant gains" in the conflict.

At an international meeting in Paris, the main opposition Syrian National Coalition (SNC) said it needs $500 million (370 million euros) in funding to set up an alternative government.

"With a state and a society collapsing, it is the Islamist groups that could gain ground if we do not do what we have to do," France's Foreign Minister Laurent Fabius warned the meeting.

"This conference has to send a clear signal, (that) it has one concrete objective: give the Syrian National Coalition (SNC) the means to act."

But the credibility of the opposition alliance has been damaged by mounting evidence that extremist Islamists are playing a central role in the campaign against Assad.

George Sabra, head of the SNC, the main body in the opposition coalition, said Assad's opponents were desperately in need of cash and arms.

"We need a minimum of 500 million dollars to be able to establish a government," he said. "And we need weapons, weapons and more weapons."

Arab and Western "Friends of Syria" agreed in December to provide a total of $145 million of support for the opposition, two-thirds of it from Saudi Arabia, but the money has yet to be delivered.

The SNC was created in November with its various components saying they would fight under a unified military command.

But some hardline groups have declined to join the coalition, saying their goal is the creation of an Islamic state to replace Assad's regime.

Assad himself said his troops have gained the upper hand against rebels in the 22-month conflict and could win in "two weeks" should Turkey stop its support for insurgents, a Lebanese newspaper reported.

"The army has a very large lead on the ground and has achieved significant gains," Al-Akhbar quoted Assad as telling "visitors" at his palace in Damascus.

The rebels' "playground is limited to some border areas with Turkey, Jordan and Lebanon, and some pockets in the countryside of the capital, which are being dealt with," particularly the airport road, said Assad.

"If the Turkish border was closed to tackle the smuggling of arms and militants, this matter would be resolved in only two weeks."

Assad said that "armed groups financed from abroad have been dealt severe blows of late."

"The United States has included the Al-Nusra Front on its list of terrorist organisations, and this move will be followed by the full liquidation of this Al-Qaeda branch."

On Saturday Al-Nusra Front claimed responsibility for a January 21 suicide bombing in central Hama against headquarters of pro-regime militiamen that reportedly killed 42 people, including civilians.

On the ground, rebels took over one of four key suspension bridges in Deir Ezzor, which straddle the Euphrates river and connect the eastern city to Hasakeh province further north, the Syrian Observatory for Human Rights said.

"The bridge is important because that it allows the army to send troops and supplies to Hasakeh," Observatory chief Rami Abdel Rahman told AFP by phone.

Fighting also erupted in a southern district of Damascus, while the army bombed rebel positions on the capital outskirts, said the Observatory, which gave a toll of 47 people killed nationwide.

The United Nations says more than 60,000 people have been killed since the start of the conflict in March 2011.

On the international front, US President Barack Obama said in an interview published on Monday that he was wrestling with a decision on whether the US should get involved to resolve the Syrian conflict.

"In a situation like Syria, I have to ask, can we make a difference in that situation?" he told the New Republic magazine.

"Would a military intervention have an impact? ... What would be the aftermath of our involvement on the ground? Could it trigger even worse violence or the use of chemical weapons? What offers the best prospect of a stable post-Assad regime?"

"And what I have to constantly wrestle with is where and when can the United States intervene or act in ways that advance our national interest, advance our security, and speak to our highest ideals and sense of common humanity."

Israel, meanwhile, moved two batteries of its vaunted Iron Dome missile defence system to the north on Sunday in case of military action against Syria or Lebanon, a security source told AFP.