The Government has changed its Illegal Migration Bill to limit detentions for unaccompanied children in a bid to prevent further setbacks to its draft “stop the boats” legislation.

The Home Office said it had introduced “safeguards” following “scrutiny” in the House of Lords – where peers inflicted 20 defeats against the controversial reforms.

Ahead of the Bill’s return to the Commons on Tuesday, an amendment has been tabled to allow immigration bail to be granted after eight days to unaccompanied children in detention, rather than the current proposed 28 days.

Another change will prevent people who have already entered the UK without permission from being removed retrospectively after the legislation receives royal assent, the Home Office said.

Measures will also be put in place to ensure the list of definitions of “serious and reversible harm” cannot be amended by secondary legislation, the department said.

A further amendment will mean that the Government keeps the current rules on the detention of pregnant women, which will mean they can only be detained for a maximum of 72 hours – though this can be extended to seven days on the authorisation of a minister.

Home Secretary Suella Braverman said: “This Bill forms a crucial part of our action to stop the boats and ensure people do not risk their lives by making illegal and unnecessary journeys to the UK.

“Today’s amendments will help this crucial legislation pass through Parliament swiftly, whilst continuing to send a clear message that the exploitation of children and vulnerable people, used by criminals and ferried across the Channel, cannot continue.”

It comes after peers demanded a series of changes to the Bill, such as reinstating right of appeal against age assessments for migrants claiming to be children and putting a legal duty on ministers to create safe and legal routes to the UK for refugees.

The upper chamber had already backed other revisions including modern slavery safeguards, a bar on backdating deportations and asylum help for unaccompanied children.

The latest defeats raised the prospect of a prolonged stand-off between peers and the Government during so-called parliamentary ping-pong, when legislation is batted between the Lords and Commons.

The Government is expected to seek to overturn many of the called-for changes, but it has now offered several concessions in an attempt to ease the Bill’s passage through Parliament.

The Bill is central to Rishi Sunak’s pledge to “stop the boats” – one of five key commitments for his leadership – which remains mired in difficulties.

Some 686 migrants were detected on Friday, the highest daily total this year, followed by 384 on Saturday and 269 on Sunday, with crossings continuing on Monday.

The provisional total for 2023 so far is about 4% lower than this time last year when around 13,200 crossings had been recorded.

Efforts to house asylum seekers on a barge moored in Portland, Dorset, have also been delayed – five weeks after Ms Braverman promised MPs it would be in place within a fortnight, the Bibby Stockholm vessel was still in Cornwall where it had been undergoing refurbishment work.

MPs also heard on Monday the Home Office is paying for thousands of empty hotel beds reserved for migrants to avoid overcrowding at processing centres.

Officials said the department keeps a “buffer” of about 5,000 beds across the country in case of a sudden influx of Channel crossings.

And the Government’s policy of sending some asylum seekers on a one-way trip to Rwanda is set for a legal battle in the Supreme Court.

Mr Sunak has said he is “throwing everything” at the pledge and insisted the Government remains “confident” that the plan is the “fair” and “right” way forward.