IDC Harmondsworth, a privately run immigration detention center at Heathrow, has been accused of a shocking loss of humanity after at least two deaths in 2012 are linked to excessive use of restraints.

The chief inspector of prisons, Nick Hardwick, said staff at the detention center blatantly ignored a doctor’s report declaring an 84-year-old Canadian, identified as Alois Dvorzac, unfit for detention or deportation.

Despite his caseworker acknowledging Dvorzac’s frail state and lack of contacts in Britain, an attempt to deport him was made on February 6, 2013. Another doctor took note of what was happening and put a stop to it, saying he was unfit to fly.

Four days later he died while still in handcuffs having been kept in them for around five hours during a visit to a hospital. The restraints were removed after his heart had stopped.

Immigration minister, Mark Harper, said: “The use of restraints in this case seems completely unjustified and must not be repeated. Clear instructions have been issued making clear that restraint should only happen where absolutely necessary.”

Chief inspector Hardwick said the security procedures at Harmondsworth, which can hold more than 600 male detainees, lacked proportionality and described the use of handcuffs as “grossly excessive.”

“Segregation was being used excessively and was not in line with the detention center rules. Disturbingly, a lack of intelligent individual risk assessment has meant that most detainees were handcuffed on escort,” Hardwick said.

He detailed several cases in which detainees who had been assessed as low risk were put in restraints before taken to appointments outside the center. On one occasion a detainee who was in a wheelchair was cuffed during a trip to hospital for no obvious reason following a stroke.

In November 2012, a dying man was wearing handcuffs while sedated and undergoing a coronary procedure in hospital. He died seven hours after his restraints were removed.

“These were truly shocking cases, and they weren’t isolated, and they reflected a culture where too often the individual human needs of the people who were being held were simply being forgotten,” Hardwick said.

“And in the worst case, this frail, elderly Canadian gentleman with dementia died in the most undignified and disgraceful circumstances possible, really.”

A spokesman for Harmondsworth said putting handcuffs on detainees was not part of a routine when taken out of the center: “However, where there is a documented risk of absconding, handcuffs may be used, balanced against a number of factors, including their age.”

“Managers have to use discretion to take difficult decisions and we have issued them with additional guidance,” he added.