A NEW parliamentary inquiry has called for a 28-day cap on the time that anyone can be held in immigration detention in the UK, to end the indefinite detention of migrants and asylum-seekers.

The All Party Inquiry into the Use of Immigration Detention in the UK said that current Home Office guidance - which said that detention should be used sparingly - was ineffective, and was not being followed.

The Liberal Democrat MP Sarah Teather, who chaired the inquiry, said: "We believe the problems that beset our immigration detention estate occur quite simply because we detain far too many people unnecessarily, and for far too long. The current system is expensive, ineffective, and unjust."

The inquiry's report, published on Tuesday, said that detention should only be an "absolute last resort", and be used only to ensure a person was removed from the country after being denied leave to remain. The UK is currently the only country in the EU not to have an upper time limit on detention. Portugal and Spain have 60-day limits, whereas Ireland has a 21-day upper limit.

The inquiry took evidence from dozens of current and former detainees, including one man who had been in detention for three years. The report said that there were "gasps of horror" from the panel as they heard some of the detainees' stories. None of them knew when they might be released from detention - a fact that caused them significant trauma.

The inquiry found that prolonged detention (30 days or more) had a serious impact on detainees' mental health, which led, in turn, to considerable costs to the taxpayer.

The inquiry panel included a former inspector of prisons, Sir David Ramsbotham, and peers and MPs from all parties. Three members of the panel visited Sweden to discuss the part played by detention in its immigration system, and they heard that there was a focus on "allowing people to leave with their heads held high". They noted that the experience of detainees in the UK was the opposite of this.

The chief executive of the Refugee Council, Maurice Wren, said that the inquiry had shone "a bright light . . . into the darkest corners of the British immigration system and . . . revealed some unpleasant secrets".

The report's recommendations included: that prisons should not be used as detention centres; that the blanket ban on social media in centres be ended; that access to health care for inmates be improved; and that those with a mental-health condition should be detained only under very exceptional circumstances.

Victims of trafficking or torture should be not be detained at all; neither should women who were victims of rape or sexual violence; nor pregnant women.

The report calls on the Government to consider community-based settings instead.

The latest figures available show that 3462 people were in detention at the end of last year, 24 per cent higher than the previous 12 months. Of those, 397 had been detained for longer than six months, 108 for more than a year, and 18 for longer than two years.

About half of those in immigration detention were asylum-seekers; others were migrants who were waiting to be removed from the UK, and those who, it was thought, might abscond if left free.

The Bishop of Croydon, the Rt Revd Jonathan Clark, who also chairs the Churches' Refugee Network, said that the report was a "searing indictment of the UK practice".

In a statement the Network emphasised that indefinite detention should be abolished. "All people who seek sanctuary should be treated with dignity and respect.  It is shocking that the Inquiry has found so many instances of this not being so in Britain," it said.

Ruth Grove-White, of the Migrants Rights Network, said: "By creating a hostile environment for migrants at any cost, the Government risks alienating communities for decades to come."

She welcomed the group's recommendations, especially the 28-day time limit. "This would have a tremendous impact on the lives of those currently held indefinitely, without any knowledge of when they might be released, and at the mercy of the Home Office."

Dr Juliet Cohen, who is head of doctors at Freedom from Torture and a frequent visitor to immigration detention centres, said: "The report gives an unflinching critique of the UK's immigration detention system. Our doctors regularly examine torture survivors who have been wrongly detained under the immigration rules, and whose health, we believe, has been significantly adversely affected by this experience. In extreme cases, our clients have turned to self-harm or attempted suicide after experiencing retraumatisation in detention."

All-Party Parliamentary Inquiries are informal cross-party groups that have no official status.