An asylum seeker from Cameroon, who has previously been persecuted due to his sexuality in his home country, claims he was assaulted by private security at Heathrow Airport.

27-year-old Marius Betondi claims the incident took place on a private plane during an attempt to remove him from Britain last month.

Mr Betondi suffered serious injuries to his eye and face – but the UK Border Agency (UKBA) says they were self-inflicted after he headbutted a seat on the plane.

“When I started screaming out they started punching me, punching my face,” he told the BBC.

He claims his nose and face started bleeding and at one point he thought he was going to suffocate as staff allegedly forced him under a seat on the aircraft.

“I did not resist them at any point because they were powerful and I was handcuffed. I was powerless and couldn’t do anything”

Scotland Yard and the UK Border Agency have both launched investigations.

Mr Betondi applied for asylum on the grounds that he faced persecution in Cameroon because of his sexuality – he says he has been gay since the age of 16.

But the UKBA did not believe him and rejected his request.

There have been four failed attempts to remove him from the UK, the latest of which took place on 18 January.

A UKBA spokesman said: “Where we and the courts find that an individual has no right to be in the UK we expect them to leave. Where they refuse we will enforce their removal.”

Last November, the United Nations Office of the High Commissioner for Human Rights (OHCHR) called on Cameroon to end the enforcement of homophobic laws.

Earlier this week, a leading human rights lawyer criticised the UK Border Agency for subjecting LGBT asylum seekers to “inhuman and degrading” pressure to “prove” their sexual or gender identity.