Saudi crown prince in U.S. for medical tests

Saudi Arabia's Crown Prince Nayef (C) arrives for the Saudi Crown Prince Cup final soccer match between Al-Hilal and Al-Ettifaq at King Fahad Stadium in Riyadh February 10, 2012.

JEDDAH, Saudi Arabia (Reuters) - Saudi Crown Prince Nayef has arrived in the United States for medical tests, Saudi state television said on Friday.

Prince Nayef, who has been the kingdom's interior minister for decades, arrived in Cleveland for "scheduled medical tests", it said, without giving further details.

At about 78, Prince Nayef is part of an ageing leadership in the world's top oil exporter, whose stability is key to the world economy.

King Abdullah appointed Prince Nayef as the new crown prince of the major U.S. ally in October, after ex-Crown Prince Sultan died of colon cancer in New York.

Nayef, who is considered a conservative even by Saudi standards for his close ties with the austere Wahhabi sect of Islam, has been a pivotal figure and supervised the daily affairs of the kingdom in the absence of the king, who has suffered from back problems.

The television said Prince Nayef had arrived in the United States from Morocco, where state media said on Thursday he had traveled for a private vacation.

Saudi liberals see him as an anti-reform force who is likely to take a cautious approach to social and political change. In foreign affairs, he is expected to focus on national security, having led the kingdom's fight against al Qaeda as interior minister since 1975.

However, former diplomats to Riyadh and some analysts say he is likely to show a more pragmatic side as crown prince, and eventually as king.

(Writing by Firouz Sedarat in Dubai; Editing by Alessandra Rizzo)