The Equality and Human Rights Commission (EHRC) said provisions in the bill that allow the detention of children and pregnant women, and remove protections for trafficking and modern slavery victims, were "particularly worrying".

Among the watchdog's key concerns are that the bill "undermines the core principle of the universality of human rights", risks "restricting the right to asylum and penalising refugees" and "insufficiently considers" the impact on vulnerable people and those with protected characteristics.

The Illegal Migration Bill is currently making its way through Parliament and is due to be heard by MPs again on Tuesday.

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The government has promised that the new bill will ensure anyone who arrives illegally in the UK is "detained and swiftly removed" by granting ministers the power to deny asylum applications from those who have entered the country on small boats.

Under the new law, the home secretary will be given the power to remove unaccompanied children from the UK once they turn 18.

The watchdog also expressed concern at the speed that the bill is being pushed through Parliament.

In recent days, Rishi Sunak has been forced to agree to a number of amendments to the bill to appease both the right and left wings of his party.

The prime minister has been under pressure from some on the right of his party to withdraw from the European Convention on Human Rights, which the European Court of Human Rights interprets, but this is not government policy.

Some MPs have blamed the court, based in Strasbourg, for thwarting the government's policy of sending asylum seekers to Rwanda after the first plane was unable to take off following a last-minute court order.

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Is the government's new Illegal Migration Bill legal?
Home secretary will be able to use 'discretion' when considering whether to follow European human rights orders

Oliver Dowden, the new deputy prime minister, confirmed on Sky News' Sophy Ridge on Sunday programme that Home Secretary Suella Braverman will be able to use her "discretion" when considering injunctions from the ECHR when they apply to deportations.

Mr Dowden denied that this would give the home office "carte blanche" to ignore European court orders.

Meanwhile, MPs on the more liberal wing of the party have sought assurances from the government that it will open up more safe and legal routes for those fleeing persecution.

Other amendments agreed by the government include giving immigration officers new powers to seize mobile phones from migrants and asylum seekers as well as forcing people who claim they are children to undergo scientific age checks.

The government has also committed to consulting local authorities within three months of the bill becoming law and to publish a report on any existing or proposed additional safe and legal routes within six months of it becoming law.