The US has moved a step closer towards arming opposition rebels in Syria.

A key congressional committee had raised concerns that US weapons could end up in the hands of fighters linked to Al-Qaeda like al-Nusra Front, but the House Intelligence Committee has now said that it is willing to accept the risks, officials said on Monday.

"We believe we are in a position that the administration can move forward," House of Representatives Intelligence Committee Chairman Mike Rogers told Reuters.

President Barack Obama had said in June that the US would begin openly supplying the rebels after two years of balking at directly sending arms to the opposition.

"We have been working with Congress to overcome some of the concerns that they initially had, and we believe that those concerns have been addressed and that we will now be able to proceed," a source familiar with administration plans told Reuters on condition of anonymity.

US army general Martin Dempsey, chairman of the Joint Chiefs of Staff, said that more than $1bn would be spent per month if the US became more involved in Syria.

Republicans and Democrats on the House and Senate intelligence committees had said that arming rebel fighters would not be enough to tip the balance the civil war against President Bashar al-Assad.

Part of the deadlock was broken on July 12 when members of the Senate Intelligence Committee who had questioned the wisdom of arming the insurgents decided behind closed doors to tentatively agree that the administration could go ahead with its plans, but sought updates as the covert effort proceeded.

Now, the House committee has also given at least a cautious go-ahead.

Success concerns

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Rogers said that there were still strong reservations.

"We got a consensus that we could move forward with what the administration's plans and intentions are in Syria consistent with committee reservations," Rogers said.

The source familiar with administration plans said: "The committees were persuaded and we will be able to move forward."

The timeline was unclear, but supporters of the rebels hope the deliveries of US-provided arms will start in August.

Louay Sakka, a co-founder of the Syrian Support Group which backs the Free Syrian Army fighting Assad, said that the rebels hoped for a large number of small weapons, such as rifles and basic anti-tank weapons.

Committee sessions on arming the rebels are classified and have been held in secret.

Senior government figures like Secretary of State John Kerry have briefed politicians privately to persuade them to back the White House's Syria strategy.

Rogers said that he still had "very strong concerns" about the plan's chances of success.

Arming the rebels would be a welcome boost to the opposition, which captured a key town in Aleppo province. Activists said that government forces had surrendered Khan al-Assal after fighters surrounded part of the town.