MPs have said they want an inquiry into the death of an Angolan man who died at London's Heathrow Airport as he was being deported from the UK.
Jimmy Mubenga, 46, fell ill, according to the security firm that was escorting him on the plane on Tuesday.
Keith Vaz, chair of the Home Affairs Select Committee, called for a full-ranging inquiry and Tom Brake MP wants the incident debated in Parliament.
A post-mortem examination on Mr Mubenga has proved inconclusive.
Scotland Yard said further tests were being carried out.
Mr Mubenga's 16-year-old son Roland said he was "angry and upset" and has claimed "it wasn't a natural death".
Mr Mubenga became unwell as he waited for the plane to leave Heathrow and was taken to the nearby Hillingdon Hospital, where he died.
Mr Vaz told BBC London: "This is a shocking incident.
"We need to know in a full-ranging inquiry why he was treated in the way he was treated. Why was he being deported while his family are still in the country?
"What steps are being taken by the airline and the immigration services to make sure they checked his medical records?
"These are very serious issues which affect every single person that is being deported."
A Metropolitan Police spokesman said the death was being treated as "unexplained", adding: "At this early stage, we believe the deceased was being deported from the UK under escort by civilian security guards."
BBC home affairs correspondent Danny Shaw said Mr Mubenga was being escorted by staff from the private security firm G4S.
Proper risk assessment
The company declined to say whether any action had been taken against staff.
Mr Brake, chair of the Liberal Democrat Parliamentary policy committee that deals with home affairs and justice, said: "We need to be absolutely certain that a proper risk assessment was carried out and we need to be certain the security firm that was used are using the appropriate restraint techniques, ones that don't endanger people's lives.
"Last week I tabled an urgent question asking for matter to be debated in Parliament, and I hope that on Monday the Speaker will allow that to take place."
The death is also being investigated by the Prisons and Probation Ombudsman.