A 31-stone passenger forced flight attendants to strip him in a toilet and wipe his backside as he allegedly 'moaned with pleasure' during a long-haul flight.

The flight attendant said the large customer, who is thought to be American, made her and her colleagues undress him in a lavatory and clean his rear, asking staff to go 'deeper', during the trip from the United States to Taiwan.

The incident took place during on a flight from Los Angeles to Taiwan's Taoyuan airport on Saturday, with the passenger - a Caucasian male - yet to be named.

The stewardess, named only as her last name of Kuo, who was also Chief Purser on the flight, said in a press conference that her crew helped to pull down the passenger's pants and wipe his backside after he finished relieving himself.

The unnamed passenger on the EVA Air flight from Los Angeles to Taiwan was accused of making the cabin crew undress him

The flight attendant, named only as Kuo, speaking at a press conference in which she told of the passenger's alleged demands

The press conference was held by the Taoyuan Flight Attendants Union in a bid to get EVA Air, which currently only employees female cabin crew, to start hiring male air stewards.

Kuo said the passenger, who she estimates weighed 440lbs or 31.4st (200 kilogrammes), boarded the plane in a wheelchair and requested he be given three adjoining seats in economy class due to his size.

As the flight was not full, he was granted his request, which later allegedly escalated to a demand to use the plane's business class lavatory because he would not fit in the economy cubical.

She says the passenger claimed an injury to his right hand prevented him from fully undressing himself in order to use the lavatory.

He therefore asked the cabin crew to pull down his pants in order for him to successfully relieve himself.

Kuo said: 'I told him we couldn't help him, but he started yelling. He told me to go in there immediately and threatened to relieve himself on the floor.

'As the passenger's genitals were now exposed, one of my colleagues brought a blanket, which I used to cover his modesty.

The 440lbs man allegedly asked staff to undress him in the plane lavatory and clean him, asking staff to go 'deeper'

'But he very angrily slapped my hand away, saying he didn't want it and only wanted me to remove his underwear so he could use the toilet.'

After granting the request, they were left further traumatized when the man called them into the cubical again in order to wipe his backside.

Kuo's chief attendant reluctantly agreed, explaining that they did not want to leave the lone passenger trapped in the lavatory.

However, the flight attendants' discomfort then turned to humiliation when he allegedly began moaning in apparent pleasure as the chief attendant wiped his backside while wearing three pairs of latex gloves.

Kuo, who was holding onto the passenger to keep in steady, recalled: 'He said: "Oh, mmm, deeper, deeper," and then accused my chief attendant of not properly cleaning his backside, requesting that she do it again.'

Kuo said her staff were left further traumatized when the man called them into the cubical

Kuo said the attendant repeated the action three times before leaving, at which point the passenger said: 'You can pull my pants back up now.'

EVA Air, which only employees female cabin crew, has said in a statement its staff are not obliged to accept demands from passengers - even those requiring special assistance.

However, the Taoyuan Flight Attendants Union, which is representing Kuo and her colleagues, argue that the problem is systemic, stemming from a service industry culture that frowns upon those who do not meet the customer's every demand.

The union has suggested two solutions: ban the passenger and others like him, and begin hiring male cabin staff.

Further statements from the airlines and the union are expected in the coming days.