WASHINGTON: Defense Secretary Leon Panetta on Thursday admitted for the first time that the Pentagon had backed proposals to arm the Syrian opposition battling to oust President Bashar al-Assad.

The idea was first floated by former secretary of state Hillary Clinton, who met privately with David Petraeus, then CIA chief, in the summer of 2012 as the fighting raged in Syria.

They proposed vetting rebel groups and training fighters in a plan which they presented to the White House, according to the New York Times, citing administration officials.

But the administration of President Barack Obama was worried about the risks of pouring more arms into the volatile conflict and rejected the idea, sticking instead to providing humanitarian assistance and non-lethal aid.

Panetta and the chairman of the Joint Chiefs of Staff, Martin Dempsey, admitted under questioning in the Senate Armed Services committee that they had both supported the idea.

"I would ask again, both of you, what I asked you last March when 7,500 citizens of Syria had been killed. It's now up to 60,000. How many more have to die before you recommend military action?" Senator John McCain asked them.

"And did you support the recommendation by then secretary of state Clinton and then head of CIA General Petraeus that we provide weapons to the resistance in Syria? Did you support that?"

"We did," replied Panetta. "We did," added Dempsey.

Panetta told AFP in an exclusive interview last week that Washington is increasingly concerned that the chaos in Syria may allow Hezbollah to obtain sophisticated weapons from the Damascus regime.

"The chaos in Syria has obviously created an environment where the possibility of these weapons, you know, going across the border and falling into the hands of Hezbollah has become a greater concern," said Panetta, who is due to retire this month as Pentagon chief.