Jordan’s King Abdullah II has had surgery on his back in Germany, the Royal Court said on Tuesday.
During his absence, Crown Prince Hussein, 27, took over his father's duties.
“The Royal Hashemite Court announces that His Majesty King Abdullah II had successful surgery to treat a herniated disc in the thoracic spine area,” it said.
The king, who is 60, needed urgent surgery to relieve pain from a slipped disc, the palace said on Saturday.
His doctors advised him to have the operation in Frankfurt. He is expected to remain in Germany for a week.
King Abdullah has had back problems dating to his time in the military, before he succeeded his father, the late King Hussein, in 1999.
State media said the injury was a result of the extreme physical activity involved in his military duties.
During his youth, the king raced cars and served as a paratrooper in the Jordanian Army.
Official media suggested that the parachute jumps were the cause of his back problems.
“His Highness Prince Hussein, the crown prince, took the constitutional oath as regent to king, in the presence of the Cabinet,” official broadcast media said on Saturday.
Prince Hussein has been given more responsibilities in the last few weeks and has been promoted in the military.
During the last few weeks, King Abdullah began a series of diplomatic initiatives to try to contain violence in Palestine.
At the end of March he travelled to Ramallah, accompanied by Prince Hussein, to meet Palestinian President Mahmoud Abbas.
He also met several senior Israeli officials in Amman.
He was last in Germany on March 15 on an official visit when he met Chancellor Olaf Scholz.