Saudi King Abdullah has had a successful back operation in Riyadh on Monday, the royal court of the kingdom said in a statement.     

The monarch is in his late 80s and has introduced cautious reforms since becoming king in 2005. He went into the King Abdulaziz Medical City in the capital Riyadh late on Sunday for an operation to tighten the ligaments around his third vertebra.

"The surgery, thanks be to God, was successful," the royal court statement, carried by the Saudi state news agency, said.

Second Deputy Prime Minister Prince Nayef, chairing the weekly cabinet meeting on Monday, told the ministers that the king was in "good health" after the surgery, SPA said. 

Saudi stability is of global concern. A key US ally, the top Opec producer holds more than a fifth of world oil reserves and is the birthplace of Islam.

Abdullah had two rounds of back surgery in the US last year after suffering a herniated disc, leading to a three-month recuperation period outside the kingdom.

The royal court did not say in its statement whether Abdullah would again require a period of recuperation.  - Reuters