A group of 13 charities has called on Camden Conservatives and Liberal Democrats to rise up against the government’s new tax on giving which threatens their very survival.

Hampstead Theatre, the Winchester Project and the Primrose Hill Community Centre are among the 13 who claim proposals to limit tax relief on charitable donations announced in the budget could cut one of their remaining life lines.

Currently unlimited donations can be made to charities tax free encouraging philanthropy, but under the new proposals tax relief on donations would be capped at �50,000 or 25 per cent of income from 2013.

The letter says: “We believe that in the current climate and with the challenges faced by our society and those striving to respond to them, to obstruct philanthropy in this way is counterproductive and deeply worrying.”

The charities complain the premise that “charitable giving is an oft-exploited form of tax evasion” is unhelpful and incorrect.

The borough’s Conservative and Liberal Democrat leaders have agreed to join the rising tide of critics of the proposals – dubbed the “charity tax” – and have pledged to put pressure on their respective parties to drop the change.

Camden Council has been forced to scale back its funding of local charities, and outside bodies – such as the Arts Council – are also feeling the pinch.

Hampstead Theatre revealed this week it will be forced to close its creative learning department over the summer to plug a funding black hole.

Last year 4,000 people from schools and community outreach programmes used the theatre’s education programme.

The theatre relies on charitable donations for a third of its �2.7million income.

Artistic director Edward Hall said: “Cuts that have been made to the cultural economy are so great that if they take away our means to attract philanthropic donations, then there is only one thing that’s going to happen.

“It will lead to an enormous shrinkage of that economy and cultural heritage. This policy is misguided and an absolute mess.”

Reverend Paul Nicholson, of St Peter’s Church and St Saviour’s Church in Belsize Park, said he relied on charitable donations for repairs to the two churches.

“If these proposals are allowed to go ahead it will impoverish these charities still further,” he said. “We would like to feel that people can give to charity without being stung.”

Paul Perkins of the Winchester Project, which has taken over Belsize Library, said: “We’re being asked to think more creatively about how we generate income and then you get hit with this.

“One pillar of funding has already been taken away and then another is threatened.”

Camden Council opposition leaders, Conservative Cllr Andrew Mennear and Lib Dem Cllr leader Keith Moffitt, both told the Ham&High they would write to their parties in support of the Camden charities to oppose the plans.