Obama arrives in S Arabia today

ROME, Mar 27 (AFP): US President Barack Obama will aim Friday to reassure his Saudi hosts on the strength of their alliance, frayed by Washington's diplomatic opening towards Iran and reluctance to use force in Syria.

Obama is expected late on Friday in oil-rich Saudi Arabia, the fourth and final stop of a tour this week after the Netherlands, Belgium and Italy.

The White House was late to announce Obama's stop in Riyadh, following his European tour, fuelling speculation on the motives of the US president's second visit since his election in 2009 to Washington's decades-old ally in the Middle East.

Dating back to the end of World War II, the relationship was founded on an agreement for Washington to defend the Gulf state in exchange for oil contracts.

OPEC kingpin Saudi Arabia is the world's top producer and exporter of oil. In 2012, it was still the second largest exporter to the United States, after Canada.

But relations have soured, with Riyadh openly criticising US policy on regional issues, which are to be discussed at a meeting followed by dinner between King Abdullah and Obama.

At the Arab League summit in Kuwait on Tuesday, Saudi Crown Prince Salman bin Abdulaziz accused the international community of "betraying" Syrian rebels, outgunned in their war against President Bashar al-Assad's regime.