Saudi Arabia on Friday reiterated its call for air strikes against Bashar al-Assad's regime in Syria, after US diplomats broke ranks with the White House to push for robust action.

Briefing journalists after talks at the White House, Saudi Foreign Minister Adel al-Jubeir said the kingdom had long urged Washington to lead a military response to undermine Assad's control.

At the Saudi Embassy, Jubeir noted that from the very start of the crisis, Riyadh had pushed for "a more robust policy, including air strikes, safe zones, a no fly zone, a no drive zone."

He said Saudi Arabia wanted to arm Syria's "moderate opposition" with ground-to-air missiles and repeated an offer to deploy Saudi special forces in any US-led operation.

Riyadh's position is not new: Saudi officials have long been discreetly critical of US President Barack Obama's cautious approach to the five-year-old conflict in Syria.

But Jubeir was speaking after the US State Department was forced to confirm that many of its own diplomats had signed a cable on a "dissident channel" calling for more robust action in Syria.

Obama is reluctant to see US forces drawn into another Middle East conflict, and many in Washington are concerned that weapons sent to the rebels fighting Assad could get into the hands of extremists.

But a lengthy US and Russian led diplomatic initiative to persuade Assad and the opposition to begin talks on a political transition has yielded only the shakiest of ceasefires.