The jobs of up to 80 staff at Hounslow Language Service are under threat after councillors agreed they should withdraw nearly 20 per cent of its funding.

The service – which provides specialist support to more than 7,000 schoolchildren from ethnic minorities to develop their English – has 105 teaching and management staff, of which 86 are qualified teachers and 19 are language assistants employed by the council.

Councillors decided at an executive meeting on Tuesday to “agree in principle” to end the council’s £686,000 subsidy next year.

At a budget meeting on March 3, Conservative Councillor Adrian Lee accused opposition councillors of creating “ridiculous stories that 20 teaching posts are going to disappear”.

But Councillor Linda Davies, lead member for children’s services and family, said in her report for the executive meeting this week that redundancy costs “could be significant”.

She said: “It could be between 20 to 80, including 15 who applied for voluntary redundancy.”

Council leader Peter Thompson said no other authority offered a subsidy to its language service, and there was no evidence this lowered the achievement of ethnic minority pupils.

But Councillor Ruth Cadbury, deputy leader of the Labour group, believed the cuts would adversely affect the life chances of children who depend on the specialist teaching.

She added: “The way it has been handled has also been a complete disaster, as the cut was taken out of this year’s budget, but will not be implemented until next year, so the education department will have to make up the difference elsewhere, so other services to schools and children will suffer.”

Councillor Lily Bath, shadow spokesman on children and lifelong learning, said: “This is another example of how the administration does not value the services the council provides for children of this borough. The department’s budget is being slashed year after year, and it is a ticking time bomb waiting to go off.”

Two parents of children at Hounslow Heath Infant School have threatened legal action if the council finally decides in the Autumn to make the cuts.