An explosive device was found on an Air France plane that forced the jet to make an emergency landing in Kenya, a senior Kenyan official said on Sunday.

Karim Rajan, a Mombasa-based journalist, said the official confirmed that an “explosive device” was discovered in the lavatory during the flight and it had now been “deactivated”.

“The airport was sealed off by security personnel after the emergency landing,” Rajan quoted the official as saying. “They have found an explosive device, but they cannot confirm exactly what it is. They are investigating.”

Several passengers were being questioned after the jet flying to Paris from Mauritius landed in the Kenyan coastal city of Mombasa.

During the flight a passenger noticed something in a lavatory that looked like “a stopwatch mounted on a box”, an official told the Associated Press news agency.

The passenger reported the device to the cabin crew, who informed the pilots, leading to the emergency landing.

The official said one of those being interrogated was the man who reported the device.

“I cannot understand about what they say. This world is crazy,” one passenger told the media in Mombasa.

Washington DC-based aviation specialist Oliver McGee told Al Jazeera that airport security protocols urgently need to be revisited around the world.

“What we’re looking at right now is a crisis in aviation security. Technology has changed. Bombs are much smaller, and terrorists have become much smarter. Right now we’re taking off our shoes and our belts – is that really enough to ensure bombs are not getting on the aircraft?” McGee said.

“We need to catch up with the technology. These passengers are very fortunate.”

Speaking at a press conference at Mombasa airport on Sunday, Kenya’s Interior Minister Joseph Nkaissery said “a few passengers” were being questioned.

Kenyan authorities were working with their French and Mauritian counterparts to determine the nature of the device, Nkaissery said.

“We are in touch with Mauritius to know how security screening of passengers was done,” he added.

The Boeing 777 landed at Moi International Airport before 1am local time (21:37 GMT).

“It requested an emergency landing after a device suspected to be a bomb was discovered in the lavatory. An emergency was prepared and it landed safely and all passengers evacuated,” police spokesman Charles Owino told the AFP news agency.

Passengers of Air France flight 463 made it off the plane safely after it made an emergency landing in Mombasa [EPA/STR]

A passenger who spoke to journalists after leaving the plane in Mombasa described the emergency landing.

“The plane just went down slowly, slowly, slowly, so we just realised probably something was wrong,” said Benoit Lucchini of Paris.

“The personnel of Air France was just great, they were just wonderful. So they keep everybody calm. We did not know what was happening,” said Lucchini.

“So we secured the seat belt to land in Mombasa because we thought it was a technical problem, but actually it was not a technical problem. It was something in the toilet.”

The Indian Ocean island nation of Mauritius, which lies about 1,000km east of Madagascar, is a favourite vacation destination for French nationals.

France has been under a state of emergency since the November 13 attacks in Paris that killed 130 people.

The Islamic State of Iraq and the Levant (ISIL) group has claimed responsibility for that and the October 31 downing of a Russian passenger in the Sinai desert that killed all 224 people aboard.

Moscow has said the crash was caused by a bomb on the plane.

Two Air France flights from the US to Paris were diverted on November 18 after bomb threats were received. No bombs were found on the planes from Los Angeles and Washington DC.