The French government has bought another 100 vehicles to help stop people from travelling by small boats to England across the Channel as part of a deal with the UK government, it has been announced. Amid a deepening political row in parliament over the growing number of people taking the hazardous route, the interior ministry in Paris said on Tuesday that it had spent a further £9m on quad bikes, 4X4s, boats and vehicles equipped with monitoring equipment. The announcement comes after it emerged that councils across the UK will be forced to care for unaccompanied children who have arrived on small boats under new rules put forward by the Home Office. Scotland’s local government minister, Shona Robison, confirmed she would be writing to UK counterparts later on Tuesday, raising concerns about proposals she described as “a retrograde step, which will create needless bureaucracy and do little to support the welfare and wellbeing of these highly vulnerable children”. The home secretary, Priti Patel, is under pressure from Downing Street and Conservative MPs to tackle the issue of Channel crossings. A statement from the French ministry said 20 vehicles have been delivered and the extra equipment will be released during 2022. The decision to impose new rules on councils follows complaints from Kent county council and others in the south of England that they are being overwhelmed by a growing number of children entering the country. A transfer mechanism for children, called the national transfer scheme, has been voluntary since it was launched in 2016. Ministers have faced repeated calls to mandate the scheme to ease the impact on local authorities on the south coast that care for the majority of the unaccompanied children. Kevin Foster, the immigration minister, said the decision to make the scheme compulsory was in the children’s best interests. The Home Office will send the UK’s 217 councils that have social service departments a letter giving them two weeks to present reasons why they should not accept unaccompanied children. According to the BBC, the letter says they will not need to accept more asylum-seeking children if they are already caring for a number that makes up 0.07% of their general child population. The government will pay councils £143 per child per night under the scheme. Boris Johnson’s spokesperson twice declined to praise Patel’s strategy on Monday, days after asking the Cabinet Office to oversee a review of the issue. A ministerial colleague of Patel’s told the Guardian he had witnessed No 10 putting her in an “incredibly difficult position” and subjecting her to “immense pressure” when, in reality, they said, stopping crossings by people seeking asylum in the UK was an intractable problem that could not be easily solved. Patel told MPs in the Commons on Monday the problem would take time to fix and that “there is no silver bullet”. She said: “The only solution is wholesale reform of our asylum system.” The number of people who have made the dangerous journey across the Channel in small boats this year is now three times the total for the whole of 2020. At least 886 people succeeded in reaching the UK on Saturday, bringing the total for the year to more than 25,700. A Home Office spokesperson said: “The government is working to ensure the needs of newly arriving unaccompanied asylum-seeking children are met. We are grateful for the continued support of local authorities to provide vital care to vulnerable children and we continue to keep the national transfer scheme under review to ensure a fair and equitable distribution of responsibility across the UK.” The SNP and refugee rights groups have reacted furiously to claims from Patel that Scotland is not doing enough to help asylum seekers, dismissing the accusation as “outrageous”.