Ministers have faced cross-party pressure to review the UK's immigration detention centres.
Liberal Democrat former cabinet minister Sir Ed Davey urged the Government to look at alternatives, while Labour's Dan Carden said minister Brandon Lewis was "completely wrong" to say Britain did not have a policy of indefinite detention.
Mr Lewis told MPs detention was an important part of returning certain immigrants, while detentions never lasted longer than reasonably necessary in order to be lawful.
Speaking at Home Office questions, Sir Ed said: "Given over half of migrants leaving detention centres are released into the community and not removed, given monitoring illegal immigrants in the community costs over 80% less than detention, and given the sheer inhumanity of Britain's immigration detention regime, many believe it's time to look at alternatives that actually work better in other European countries."
Mr Lewis said he did not recognise the picture outlined by the former energy secretary, adding: "Apart from the fact that we do not have indefinite detention in this country, our policy is that there is always a presumption of liberty and that individuals are detained for no longer than is necessary.
"In fact, to be clear, some 93% left detention within four months, but we are always looking at best practice."
Labour backbencher Mr Carden (Liverpool Walton) said: "It's completely wrong to say we don't have indefinite detention.
"If you're locked up without being given a timeframe for when you're going to be released, that is indefinite detention."
He went on to renew calls for the Government to introduce a 28-day cap on detention periods.
Mr Lewis said: "Detention is an important part of our process. It's an important part of being able to enable returns.
"But we have to be very clear. To be lawful in this country, detention never lasts longer than is reasonably necessary to achieve the purpose for which it was authorised, and that is to return somebody.
"That is the policy that we want."
Tory former minister Christopher Chope asked Mr Lewis: "Would he agree that there are too many people in detention centres who should have been already deported, because they should have been deported before the expiry of their prison sentences.
"Why isn't that happening?"
Mr Lewis said a record number of almost 6,500 people had been returned from the prison population over the summer.
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