Celtic fans arriving back in Glasgow have denied they triggered "a riot" after their plane made an emergency landing at Cardiff airport.

Aviation officials and police said there were two incidents on a charter Boeing 737 returning to Scotland after the team's Uefa Cup game against Celta Vigo.

Six men from Glasgow, aged between 37 and 51, who were arrested, have been released on bail.

Charter airline company Astraeus said the trouble on Friday afternoon began when a passenger started smoking in the toilets.

The first time we knew there was something wrong was when everyone was told to put on their seatbelts and the plane nose-dived Passenger Ryan Kerr

Those fans not detained by police were put on a bus and arrived in Glasgow on Saturday at 0700 GMT after an eight-hour coach journey.

They claimed the airline had overreacted.

David McKenna, 40, held up a piece of paper reading "not guilty".

He said: "They certainly overreacted. Nothing happened on that flight. It is just unbelievable, we never expected this."

Passenger smoking

Another passenger claimed the plane experienced engine trouble during its flight from Spain.

One supporter said the plane then nose-dived and the air stewards became animated.

John McGinn, 65, of Glasgow, said: "The pilot made no announcement whatsoever. We thought the plane was coming down."

Another passenger, Ryan Kerr, 26, said: "Everyone was in good spirits and having a laugh.

"The first time we knew there was something wrong was when everyone was told to put on their seatbelts and the plane nose-dived.

"Because we had engine problems earlier, I thought there was something wrong with the plane and we were going down. It was terrifying."

'Full emergency'

He claimed the incident was the "biggest waste of taxpayers' money".

But Iain Macauley, spokesman for Astraeus, said there had been two disturbances on the aircraft.

The first, at the front, involved a passenger smoking, he said.

"A senior cabin crew member pointed out that it was against air travel regulations to smoke on the aircraft.

"This passenger objected to being asked to extinguish his cigarette."

The bus arrived in Glasgow on Saturday

He said the second incident occurred at the rear of the aircraft cabin, after the captain made an announcement that the behaviour at the front of the aircraft would not be tolerated.

Mr Macauley said: "A number of passengers at the rear of the aircraft objected strongly, one female passenger becoming particularly agitated, and at least 10 other passengers became involved.

"In the ensuing fracas the cabin crew member was struck on the arm."

The cabin crew felt matters were threatening the safety of the aircraft and the pilot made the decision to divert to Cardiff, he said.

He added that alcohol was consumed by some of the passengers onboard, although it had been forbidden.

Club's vow

He said the captain, who has 25 years' flying experience, and his crew were "extremely shaken" by events.

The pilot issued a "mayday" distress call and diverted to Cardiff, and an RAF Sea King helicopter was scrambled.

Armed police, firefighters and ambulance teams were waiting at Cardiff airport, which had swung into "full emergency" mode, when the flight landed.

Celtic chief executive Ian McLeod said any fans convicted would be banned from future international travel and the club's ground.

He said: "These individuals will have clearly undermined the reputation of the Celtic support. Such action will not be tolerated by Celtic."