RIYADH // King Abdullah bin Abdul Aziz will travel to the United States today for medical tests following the discovery that a blood clot has formed near his spine, according to the official state news agency.
Crown Prince Sultan Abdul Aziz, next in line to the throne, was due to return to Saudi Arabia from a stay in Morocco late yesterday.
The king's underlying ailment, a herniated disc that has left him in considerable pain for some time, did not appear life-threatening.
Still, his health is closely watched because of his age and the possibility that a setback would trigger an uncertain royal succession in the world's largest oil exporter and a major spiritual centre for 1.5 billion Muslims. The king, believed to be 86 or 87, has suffered heart problems in the past.
Crown Prince Sultan, who is about 80 years old, has been ill for some time. He spent more than a year getting treatment in the US and convalescing in Morocco, before returning to the kingdom last December. In August, he returned to Morocco.
Prince Nayef bin Abdul Aziz, who is the interior minister and second deputy prime minister, has not been formally named crown-prince-in-waiting, though many Saudis assume that he will succeed Sultan eventually.
The Governor of Riyadh, Prince Salman bin Abdul Aziz, will have a major say in a succession and was due to return to Riyadh yesterday as well, according to the online Saudi news journal, Elaph.
Prince Salman has been recuperating abroad after undergoing spinal surgery in the United States this summer, the state news agency reported in August.
Yesterday's announcement of the king's travels to the US comes after a series of official statements this month about his health, which the royal court said were made in compliance with the monarch's "principle of transparency".
While the Saudis' idea of transparency about their leader's health comes nowhere near the details provided to the press about a US president, King Abdullah is being more open than his royal predecessors.
Four days after he missed chairing a November 8 cabinet meeting, the royal court disclosed that he was suffering from a herniated disc and that his doctors had ordered him to rest. He then delegated his ceremonial responsibilities presiding over this year's pilgrimage to Prince Nayef.
Seeking to reassure the public that the king was not incapacitated, however, Saudi television showed him receiving well-wishers on Tuesday and joking about his condition. Noting that the Arabic name for herniated disc is close to the phrase "women's nerve," he said he did not know how he got his ailment since "we have not seen but only good things from women."
On Friday, after experiencing an increase in pain, he had more tests.
"It appears he has a blood clot in addition to his slipped disc, which is pressuring the nerves so the medical team advised him to rest and monitor the situation," said a court statement carried by the official Saudi Press Agency.
Two days earlier, King Abdullah had taken the long-expected step of appointing his son, Prince Miteb bin Abdullah, commander of the Saudi National Guard, a post that the king has held since 1962.
The promotion was widely seen as a boost for Prince Miteb in succession negotiations within the royal family.
According to Egyptian newspapers, Egyptian President Hosni Mubarak had been scheduled to meet King Abdullah in Riyadh on Saturday, though the visit was never officially announced by the Saudi court.
Instead, Mr Mubarak spoke with the Saudi monarch by telephone Saturday night, Saudi papers reported.
The Saudi announcement yesterday did not say what US medical facility the king would enter. One Saudi source suggested it might be Presbyterian Hospital in New York. Previously, the king has had check-ups at Minnesota's Mayo Clinic.