An emergency landing of an Air France flight from Mauritius to Paris in Kenya was caused by a false bomb alert, the airline's chief says.

Frederic Gagey told a news conference that the suspected package turned out to have been made of paper and a timer.

The pilots of the Boeing 777 requested to land at Moi International Airport in Mombasa after the item was found in a toilet.

Both the aircraft and airport were safely evacuated.

Gagey told journalists that the device appeared to be made of a carton, sheets of paper and some sort of kitchen timer, and placed behind a mirror in a toilet.

He said the device had had no explosives, it would not have been detected during pre-flight security checks in Mauritius, and passengers and crew had not been at risk.

He thanked the crew and the Kenyan authorities for the way they had handled the incident - the fourth such false alarm since the 13 November Paris attacks.

A police official quoted by AP news agency said a passenger had noticed an object in the toilet that looked like "a stopwatch mounted on a box".

Gagey said the crew was alerted, and the pilots informed. The pilots decided to land at the nearest airport.

Joseph Nkaissery, cabinet secretary at Kenya's ministry of interior, said authorities from France and Mauritius had been helping with the investigation.

The plane was carrying 459 passengers and 14 crew members and had left Mauritius at 01:00 GMT.

It had been due to fly directly to Charles de Gaulle airport in Paris.

One of those on board, Benoit Lucchini, said passengers were calm and were told by the crew that the plane was being diverted because of a technical problem.

"The plane just went down, slowly, slowly, slowly, so we just realised probably, something was wrong," he said.

"But the personnel of Air France were just great, just wonderful. So they keep everybody calm and really quiet."

France is still on high alert following bomb attacks and shootings in Paris last month that killed 130 people.

So-called Islamic State (IS) said it carried out the attacks in response to France's military action in Syria.