GENEVA (AFP/REUTERS) - US Secretary of State John Kerry has broken his leg in a cycling accident but the injury is not life-threatening, a State Department spokesman has said.

He was expected to make a full recovery, the spokesman Mr John Kirby said, adding that he was in "stable condition" and will return to the United States for treatment.

Mr Kerry broke his right femur in the accident in Scionzier near Chamonix in the French Alps.

He was due to travel to Madrid, Spain, later on Sunday before heading to Paris for a meeting with Iraqi Prime Minister Haidar al-Abadi and members of a US-supported coalition fighting the militant group Islamic State in Iraq and Syria.

Those visits are now cancelled.

"Given the injury is near the site of his prior hip surgery, he will return to Boston today to seek treatment at Massachusetts General Hospital with his doctor who did the prior surgery," Mr Kirby said.

The accident occurred earlier on Sunday while Mr Kerry was out cycling the day after meetings with his Iranian counterpart Mohammad Javad Zarif in Geneva to try to overcome obstacles in negotiations on curbing Teheran's nuclear programme.

He was flown by medical helicopter from the scene of the accident to Geneva's main public hospital.

"He did not lose consciousness," Mr Kirby said earlier, adding that paramedics and a doctor were on the scene with Mr Kerry's motorcade at the time of the accident.

The accident occurred at around 9.40am local time.

The 71-year-old secretary of state is an avid cyclist and often takes his own bike on official trips abroad.

A senior State Department official said it appeared Mr Kerry hit a curb and there was no vehicle involved in the accident.