U.S. Secretary of State John Kerry plans to fly to Boston Monday after staying overnight in a Swiss hospital to receive treatment for a broken leg incurred in a bicycle crash. It was unclear how long he will be grounded once he returns to the U.S.

Kerry fractured his right femur Sunday when he struck a curb with his bicycle and fell on a regular Tour de France route about 40 kilometers (25 miles) southeast of Geneva.

Kerry was in stable condition and was receiving treatment at Geneva’s main medical center, HUG. He was to receive further care at Massachusetts General Hospital once he returns home.

“It was sensible for him to remain in the hospital for observation overnight for purely precautionary measures,” U.S. State Department spokesman John Kirby said. “The secretary continues to be in great spirits and active. He has done a range of phone calls including with the president.”

He “never lost consciousness, his injury is not life-threatening and he is expected to make a full recovery,” Kirby said in an earlier statement.

Kerry, 71, was taken by helicopter to the Geneva hospital after a paramedic and a physician who were traveling with his motorcade at the time of crash provided him with immediate attention. X-rays confirmed the extent of his injury.

His regular government plane returned Sunday night to the United States carrying much of his staff and reporters who had accompanied him on the trip. He had hoped to leave later in the day on a plane fitted with special medical equipment.

Kerry’s cycling rides have become a regular occurrence on his trips. He often takes his bike with him on the plane and was riding that bicycle Sunday.

He was in Geneva for six hours of nuclear negotiations with Iranian Foreign Minister Mohammad Javad Zarif on Saturday. World powers and Iran are trying to seal a comprehensive accord by June 30.

The prospect of a lengthy rehabilitation for Kerry could hamper the nuclear talks and other diplomatic endeavors. Even if he does not need surgery, it was not immediately known when he could fly again after returning to the United States.

There was no word on whether he would need an operation.

Kerry had planned to travel to Madrid on Sunday for meetings with Spain’s king and prime minister, before spending two days in Paris for an international gathering to combat the Islamic State. He will participate in the Paris conference remotely, Kirby said.

(AP)