Migrants who have managed to reach Britain from Calais are being driven to new homes in London by taxi for up to £150 a time at the taxpayers' expense, it has been reported.

One taxi driver for a Dover-based firm said the company had made 'seven or eight' 70-mile journeys to the capital in the last week - resulting in a bill that could reach £1,200.

Most of the journeys are believed to involve migrants who are under 18 to specialist temporary accommodation.

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Costly operation: A taxi driver for a Dover-based firm has said that migrants who have managed to reach Britain from Calais are being driven to London by taxi for up to £150 a time at the taxpayers' expense

Taxpayer burden: Most of the journeys are believed to involve migrants who are under 18 to specialist temporary accommodation. A migrant is seen scaling a security fence of a Eurotunnel terminal near Calais

They are being paid for by Kent County Council's social services department, according to the Daily Telegraph.

A spokesman for the authority said: ‘It has been necessary to transfer some by taxi, for which charges of up to £150 are not unusual, depending on distance.’

The move has been deemed necessary because the council has run out of suitable accommodation to house migrants in its own district and is therefore having to send them further afield.

The number of asylum-seeking children is said to have rocketed from 368 in March to 629 at the end of last week - putting local services at 'breaking point'.

Last week it was revealed that social workers in Kent were struggling to find foster parents for scores of unaccompanied children who had been abandoned by migrants.

Many of the youngsters, said to be traumatised and unable to speak English, are being held in special centres while long-term care is arranged.

Their arrival has significant implications for the taxpayer, a local government chief warned, because councils are responsible for all costs associated with child asylum seekers until they are 25.

This includes schooling, foster care or children’s homes, through to university fees and housing costs.

Peter Oakford, Kent County Council’s cabinet member for children’s services, last week told Radio 4’s Today programme: ‘The biggest problem we have is the number of 16 and 17-year-olds coming over that we need to put through a reception centre, we need to conduct the assessments on these young people because they have had some very traumatic experiences.

Desperate measures: It is being done because Kent County Council has run out of suitable accommodation to house migrants in its own district and is therefore having to send them further afield

'We need to find placements for them in the community. Every young person who has come into the care of Kent County Council we have found a place for thus far, but we are now struggling.

‘Our numbers have doubled in the last few months.’

A government spokesman said the taxi journeys were ‘a matter for the council’.

Meanwhile, MPs have been warned that as many as 70 per cent of the thousands of migrants massing at Calais are making it to Britain.

Kent Chief Constable Alan Pughsley said police accurately knew only the number of migrants who are caught in the UK – which was more than 400 in his county alone over a recent five-week period – but added that the true figure was likely to be ‘a lot higher’.

Mr Pughsley said: ‘Having consulted with our French colleagues, they have confirmed that through their own research, 70 per cent of migrants they process in the area of Calais leave the vicinity within a four-month period.'

Based on the assumption that the migrants make it to the UK, rather than give up after trekking thousands of miles to reach Calais, it would mean as many as 3,500 of the 5,000 currently in the town will get through. Over the course of a year, it is the equivalent of 10,500 – or 900 a month – making it across the Channel.