WASHINGTON: Secretary of State Hillary Clinton heads Saturday to Qatar and Saudi Arabia to build the US case for tougher sanctions over Iran's nuclear plans in meetings with key Arab and Muslim leaders.

Clinton will also pursue the Obama administration's bid to promote Arab-Israeli peace and "turn the page" on ties with Muslim countries -- the latter in a speech to the US-Islamic World Forum in the Qatari capital Doha.

She is departing a day later than planned after her husband Bill Clinton, the former president, had a heart operation on Thursday, but the delay will not cause her to miss any of her meetings, State Department officials said.

Clinton may ask the Saudis -- whom she sees Monday and Tuesday following a speech to the US-Islamic World Forum -- to offer the Chinese increased oil supplies to try to win Beijing's backing for sanctions against Iran.

China imports much of its oil from Iran.

"I wouldn't rule it out that that might be part of the discussions," a senior State Department official told AFP when asked whether the chief US diplomat would make such an appeal to the Saudis to win over China.

China appears to be the sole holdout to sanctions among the five veto-wielding members of the UN Security Council, which is also composed of the United States, Russia, Britain and France.

Moscow has hardened its stance toward Iran lately.

During her stop in Riyadh, Clinton is set to meet Saudi Arabia's King Abdullah bin Abdul Aziz Al-Saud and Foreign Minister Prince Saud Al-Faisal. She will meet other Saudi officials in the Red Sea port of Jeddah.

In Doha, she is to meet Sheikh Hamad bin Khalifa Al-Thani, Qatar's emir, and Sheikh Hamad bin Jassim Al-Thani, who is both foreign minister and prime minister.

"Middle East peace will be an issue that will be discussed. Iran certainly will be an issue that is discussed," Crowley said while declining to enter into details about either topic.

She will also hold similar talks with leaders attending the seventh US-Islamic World Forum, including Turkish Prime Minister Recep Tayyip Erdogan, Crowley told reporters.

Turkish Foreign Minister Ahmet Davutoglu will, according to a Turkish diplomat, visit Iran next week to push for a diplomatic solution to the nuclear stand-off.

Iran said on Tuesday that it had started the process of producing 20 percent enriched uranium.

The move coincides with Western efforts for Iran to commit to a proposal to ship its low-enriched uranium (LEU) in return for nuclear fuel for a Tehran medical research reactor.

Although Iran has said it is ready "in principle" to sign on to the proposal, it insists that not all its LEU be shipped out in one go as world powers are demanding.

The West fears the uranium program masks a drive to build an atomic bomb, while Iran denies the charge and says its goal is the peaceful use of nuclear power.

Turkey, the only NATO member that neighbors Iran, insists the row should be resolved through dialogue, arguing that economic sanctions or military action against Iran would have a damaging impact on the whole region.

China has taken a similar stand.

Aaron David Miller, a former Middle East advisor in past US administrations, doubts the Saudis would offer oil guarantees to China, whose economy is growing rapidly, to encourage Beijing to change its stance on sanctions.

Miller told AFP he does not foresee "the sort of perfect storm of elements required to get the Saudis in a position where they are going to do something big which cost them much with the Chinese."

Nor does he see Saudi Arabia having an interest in increasing output to reduce oil prices and hurt Iran economically.

Miller said US-Saudi ties have eroded since the September 11, 2001 attacks -- which involved many Saudi members of Al-Qaeda -- and Obama has disappointed Riyadh with his failure so far to revive Arab-Israeli peace talks.

US officials said Clinton would also likely raise concerns with the Saudis and others about Al-Qaeda in the Arabian Peninsula, based in Yemen.