Imposing VAT on international schools in the UK could lead to hundreds of pupils leaving, European diplomats have said, as they called for the institutions to retain the exemption from the 20% duty that private schools are expected to lose.

The German and French ambassadors to the UK, Miguel Berger and Hélène Duchêne, said international schools were distinct from British private schools because the option of transferring to the British state sector was not always realistic for their pupils.

“For expats coming here for two, three or four years wanting their children to go back to the national system, their only option is to go to these schools,” Berger said.

He told the Times: “We would really like to see the British government recognise the importance of these schools – not only for our political and cultural relations but also for the people this will affect.”

From January, the government plans to remove the VAT exemption and business rates relief for private schools to enable funding for 6,500 new teachers in state schools. Currently, independent schools do not have to charge 20% VAT on their fees because there is an exemption for the supply of education.

Berger said executives of companies that invest in the UK “must know they can send their children to a German school”. He said Deutsche Schule London, based in Richmond in the south-west of the capital, had about 900 pupils and that “between 20% and 25% might be obliged to leave” if the change was introduced.

He added: “The German state covers 30% of the costs of the school and 50% of the investment, so there is a lot of state funding that goes into the school.”

Critics of the VAT change have expressed concerns about the short timescale involved and the risk of unintended consequences such as the potential impact on children with learning difficulties who attend specialist independent schools and on military families.

Eleven schools in the UK are accredited by the French education ministry, nine of which are in London. Duchêne said these schools would be weakened by the VAT change.

She said: “We are not asking for an exemption: we are not the target of this VAT measure. Our schools are different from the target ones since we follow special courses preparing for French exams. These parents don’t have a plan B because other schools don’t follow the French curriculum.”

She said 6,300 pupils could be affected in the UK, adding that the change was “not in line with the reset to our relationship which the British government has instigated”. She said imposing VAT on the schools “could also be an issue for our companies, as they need these schools for employees coming to work here”.