Witnesses said Mubenga had complained he was unable to breathe before he died [Guardian

A UK police homicide unit has taken over the investigation into the death of an Angolan man on board a plane as he was being forcibly deported at London's Heathrow airport earlier this week.

Passengers on the British Airways flight to Luanda, the Angolan capital, said they saw Jimmy Mubenga, 46, being heavily restrained by security guards on the plane.

Members of the British parliament have called for an inquiry into the death of Mubenga, a father of five.

It is the first such incident since Joy Gardner, who was to be deported back to Jamaica, died after being gagged and restrained by police at her home in London in 1993.

The death of Mubenga, who lost a legal appeal to remain in Britain in August, is being treated as unexplained.

Eyewitnesses said he had complained he was unable to breathe before he died.

Speaking to the Guardian, a British newspaper, Roland Mubenga, Jimmy's son, said: " I want the truth to come out, that's all I want, the truth to come out.

"So I know that I know how, how my father passed away and everything. So I can just at least, every time I think of my father, I can think about the happy things and know, instead of wondering what happened."

'Arbitrary targets'

The officers involved in the Gardner case were found not guilty of manslaughter but the Metropolitan police's specialist deportation squad was disbanded.

The role of carrying out forced deportations was subsequently contracted by the UK Border Agency to private security firms.

G4S, Britain's largest security company, is in charge of most of the 10,000 forced deportations made every year and took part in the deportation of Mubenga.

In 2008, a report investigated allegations of 300 cases of abuse and excessive force against deportees in the UK.

The cases were examined by Dame Nuala O'Loan, a former independent Northern Ireland police ombudsman.

O'Loan's report, published in March this year, rejected the claim of "systemic abuse" saying there was no pattern of inappropriate force by any individual.

However, she did criticise the UK Border Agency for not properly investigating complaints of abusive treatment.

Speaking to Al Jazeera, Emma Ginn, a co-ordinator for Medical Justice, one of the organisations behind the 2008 report, said: "The private sector companies, I think, are really mainly concerned with profit and their business is to deport people."

"It's also driven by the fact that there are arbitrary targets on deportations, which shows that there's no relation to the actual individual protection needs of the people concerned.

"We feel this is really serious, a man [Mubenga] has now paid with his life, we think they should suspend all forced departures pending a full public inquiry."

Source: Al Jazeera and agencies