RIYADH — US Secretary of Defence Robert Gates was holding talks in Riyadh on Wednesday with Saudi King Abdullah, with both sides concerned by Iranian intentions in the region and spiralling unrest in Yemen.

"Iran will be a major focus of their conversations, both in terms of the regional threat they pose but also lately in the role they've been playing in trying to exploit the unrest in the region to their advantage," Pentagon spokesman Geoff Morrell said ahead of the meeting.

And although Washington and Riyadh have had differences over their responses to the wave of Arab uprisings, Morrell said that "the secretary has developed and enjoys an excellent relationship with King Abdullah."

Saudi Arabia and other Gulf Arab states have traded accusations with Iran of meddling and interference, especially over the tiny Sunni-ruled, Shiite-majority kingdom of Bahrain that lies to Saudi Arabia's east, and is a key US ally and home to the US Fifth Fleet.

Saudi Arabia led a joint Gulf force that deployed there last month, enabling Bahraini authorities to quell Shiite-led protests calling for democratic reforms.

On Sunday, foreign ministers from the Gulf Cooperation Council (GCC), of which Saudi Arabia is a leading member, accused Iran of interference in the affairs of Bahrain and Kuwait in a campaign to destabilise the region.

Iranian President Mahmoud Ahmadinejad responded by saying that the United States and its allies pressured the Gulf Arab states to make the accusations against Iran, and demanded Saudi forces leave Bahrain.

The meeting, which will be Gates' first with King Abdullah since the monarch returned home in February after months of treatment abroad for a back ailment, also comes amid mounting international anger over bloodshed in the kingdom's southern neighbour Yemen and pressure on its president to stand down.

Yemeni President Ali Abdullah Saleh, a close US and Saudi ally, has faced months of protests calling for his departure, in which around 125 people have been killed.

Despite Saleh being a key US partner in its fight against Al-Qaeda, the White House on Tuesday issued an unusually personal warning to him about violence against Yemeni protesters.

"The Yemeni people have a right to demonstrate peacefully, and we remind President Ali Abdullah Saleh of his responsibility to ensure the safety and security of Yemenis who are exercising their universal right to engage in political expression," White House spokesman Jay Carney said.

The GCC is seeking to mediate between the Yemeni government and the opposition in a bid to find a way out of the country's political impasse.

Saleh on Wednesday welcomed the mediation offer, according to a statement on Saba state news agency, which said he "affirmed the necessity of a serious and fruitful dialogue to overcome the current crisis."