US President Barack Obama has sought to reassure Saudi Arabia's King Abdullah that he will support moderate Syrian rebels and reject a bad nuclear deal with Iran, during a visit designed to allay the kingdom's concerns.

Flying by helicopter to the king's desert camp on Friday, Obama underscored the importance of Washington's relationship with the world's largest oil exporter in a two-hour meeting that focused on the Middle East but did not touch on energy or human rights.

Last year, senior Saudi officials warned of a "major shift" away from the US after bitter disagreements over its response to the Arab uprisings, efforts to negotiate with Iran, and Washington's decision not to intervene militarily in Syria, where Riyadh wants more American support for rebels.

While the two leaders discussed "tactical differences", they both agreed their strategic interests were aligned, a US official told reporters after the meeting.

"I think it was important to have the chance to come look him [King Abdullah] in the eye and explain how determined the president is to stop Iran from getting a nuclear weapon," the official said.

The meeting was a chance to assure the king that the US "won't accept a bad deal and that the focus on the nuclear issue doesn't mean we are not concerned about, or very much focused on, Iran's other destabilising activities in the region".

Aiding Syrian rebels

The leaders had a full discussion about Syria, where a three-year-old civil war has killed an estimated 140,000 people and uprooted millions.

The official said both countries shared the objective of a political transition in Syria and supporting moderate opposition to Assad.

Riyadh has long differed from Washington about Obama's reluctance to supply rebels with surface-to-air missiles, sometimes known as MANPADS.

The Washington Post reported on Friday that the US was ready to increase covert aid to Syrian rebels under a new plan that included training efforts by the CIA, and was considering supplying MANPADS.

The White House has not closed the door to the possibility of such a move in the future, but officials said US qualms about providing those weapons to rebels had not changed.

"We have made clear that there are certain types of weapons, including MANPADS, that could pose a proliferation risk if introduced into Syria," deputy national security adviser Ben Rhodes told reporters on Air Force One during Obama's flight from Rome to Riyadh. "We continue to have those concerns."

US officials said Obama did not have time to raise concerns about the kingdom's human rights record. They said Washington would continue to press Riyadh about its concerns, which include women's rights.

Source: Al Jazeera and agencies