RIYADH (Reuters) - Saudi Arabia's veteran foreign minister has undergone successful spine surgery in the United States, state media said.

Prince Saud al-Faisal, a member of the ruling Al Saud family, would be expected back "soon" after the end of an unspecified recuperation period, the state news agency SPA said late on Saturday. It gave no more details.

Saudi Arabia is an absolute monarchy with no elected parliament. It is the world's largest oil exporter and has long been an ally of the United States in the Middle East. Al Qaeda launched a failed campaign of violence to destabilize the ruling family from 2003 to 2006.

Crown Prince Sultan has been out of the country since November when he went to unspecified surgery. He has been in Morocco since April for "rest and recreation," state media said at the time.

In March, King Abdullah appointed Interior Minister Prince Nayef bin Abdul-Aziz as second deputy prime minister, a promotion that would normally place him second in line to the throne after Sultan.

The position means he will run the kingdom when both the monarch and crown prince are away.