The government has been accused of locking up innocent migrants for its own “administrative convenience” – after it was revealed 20 people have been held without trial for at least two years.

One detainee has been in custody awaiting deportation for 1,701 days - almost five years - and three more have been held for three years.

The US has been widely condemned for detention without trial in Guantanamo, yet the UK stands revealed as locking up migrants for comparable periods in immigration detention centres.

Jerome Phelps, director of Detention Action

Figures released by the Home Office yesterday after a freedom of information request reveal that 20 migrants have spent at least 722 days in detention under immigration powers.

In numbers:

£4.8m

Sum paid by the Home Office in 2013/14 in compensation for unlawful detention.

3,378

People detained solely under Immigration Act powers by September 2014 - meaning they are not serving time for a criminal offence.

53.7

Combined total of years spent in centres by Britain’s 20 longest-serving migrants in detention.

4

Number of individuals in detention for more than three years – in one case, for more than four-and-a-half years.

90

Individuals held in detention centres for more than one year

60%

More than 60 per cent of migrants who are detained for more than a year are ultimately released, not deported, according to Mr Phelps.

Removal centres such as Yarl’s Wood have faced allegations of abuse and mistreatment of inmates by staff. Prolonged incarceration poses a serious mental-health risk to detained migrants, many of whom are later allowed to stay in the UK.

Most of those in detention are asylum-seekers, while others may be those whose visas may have run out, say campaigners. Some will be in detention because they are ex-offenders and considered a “flight risk”.

I was detained for three-and-a-half years. It was worse than the physical torture I experienced in my country, because with the torture you get a break between beatings. You never know when the psychological pain of detention will end.

Abdal, a former detainee from Sudan

These 20 people... have been deprived of their liberty for the administrative convenience of the Home Office.

Don Flynn, director of Migrants’ Rights Network

It is disgraceful that some people are being detained for over four years. No visa or asylum application process should take that long. People should either be granted leave to stay in the country or, if they don’t have a right to be here, they should be deported. Such long detention periods benefit nobody – it is traumatic for those being detained and it is incredibly expensive.

Yvette Cooper, shadow home secretary

Detention is used as a last resort when an individual will not leave voluntarily or when there is a risk they will abscond.