More than 300 migrants arrived in the UK after crossing the Channel on Sunday as a seven-year-old girl drowned while trying to make the journey.

The child had been travelling with her pregnant mother, her father and three siblings in a boat carrying 16 people when she died after it capsized, according to the French coastguard.

The Prefet du Nord said another couple, two men and six young children were also on board when the boat got into difficulty in the early hours of the morning off the French coast.

They were all taken to hospital in Dunkirk.

The Home Office recorded 327 people arriving in the UK after making the journey in eight boats that day, suggesting an average of around 41 people per boat.

This takes the provisional number of arrivals for the year so far to 2,582, with this number expected to rise as crossings continued on Monday.

It comes as Rishi Sunak defended his stalled plan to send migrants to Rwanda as a “worthwhile investment”, despite the public spending watchdog revealing the cost of the policy could soar to half a billion pounds.

Last week the National Audit Office (NAO) said the deportation plan could cost taxpayers nearly £2 million for each of the first 300 asylum seekers sent to the east African nation, prompting Labour to brand the news a “national scandal”.

The Home Office had so far refused to say how much more money, on top of the £290 million already confirmed, the UK has agreed to pay Kigali under the initial five-year deal but the NAO report uncovered millions more in spending, including £11,000 for each migrant’s plane ticket.

The Prime Minister is trying to revive the flagship asylum scheme – central to his pledge to stop Channel crossings – and prevent more legal challenges by pushing through legislation which will declare Rwanda a safe country while also ratifying a new treaty.

The Rwanda Bill returned to the House of Lords on Monday, with a series of votes expected.

The Law Society of England and Wales warned no evidence has so far been provided to demonstrate it is safe to send asylum seekers to Rwanda.

But Downing Street said the Government remains committed to sending flights to Rwanda “in the spring”.

Meanwhile campaigners have called for an independent inquiry into the treatment of lone migrant children in the wake of a series of “disturbing findings” by the sacked borders and immigration watchdog.

Charities and frontline workers from organisations including the Refugee Council, British Association of Social Work, the Immigration Law Practitioners Association and the Fostering Network published an open letter which brands David Neal’s conclusions “disturbing, distressing and dystopian”, adding: “There is a culture of callous disregard for children’s basic right to dignity.”

The Government belatedly published a raft of reports last week which had been produced before Mr Neal was fired.

Among a series of criticism of Home Office operations, Mr Neal raised concerns about the experiences of unaccompanied asylum-seeking children (UASC), for whom the UK has a legal duty of care.

There were several instances where “bread-and-butter checks” were not being carried out in hotels where children were being housed, Mr Neal said.

He described another example, in which youngsters had to play a game to find out who would next be placed in foster care, as “insensitive in the extreme and undoubtedly upsetting to the children”.

Mr Neal previously told MPs he was sacked “for doing my job” after the Home Office said he lost the confidence of the Home Secretary James Cleverly amid claims he breached the terms of his appointment.

In the Commons, MPs responded with laughter as legal migration minister Tom Pursglove insisted the Government had delivered on its commitment to publish the overdue watchdog reports while Labour’s shadow home secretary Yvette Cooper accused Mr Cleverly of going into hiding after he “shamefully tried to bury or hide” the slew of findings.

A Home Office spokeswoman said: “The safety and welfare of unaccompanied asylum-seeking children is our utmost priority. Following the inspections findings, we launched a full investigation into the inappropriate behaviour of the support worker, who was removed from site immediately and did not return.

“Since the two ICIBI (Independent Chief Inspectors of Borders and Immigration) inspections in 2022 and 2023, we have closed all seven hotels used to accommodate unaccompanied asylum-seeking children.”