Charities are being forced to drop fundraising activities because they cannot afford exorbitant public liability premiums, a specialist broker has warned.

Witney-based broker Harrison Beaumont specialises in outdoor activity risks, ranging from extreme sports like white water rafting, canyoning, skydiving and base-jumping to charity events such as church car boot sales and village fairs.

Managing director Peter Beaumont said that Trenwick had pulled his liability binder with a month's notice after four years' successful partnership.

Now, he said, each risk has to be submitted separately to the underwriter, which was unfeasible for many of his small risks.

"We sent them 400 renewals in one month and they just couldn't cope," he said.

"We lost a third of our business over night."

Beaumont said many of his clients had gone bust because they were unable to find cover, while others faced premium rises of up to 700%.

"They're whacking on silly figures, even people like us, who've been in the business 30 years," he said.

"There's no call for it."

He said charities were hardest hit by the rises, such as the Charlbury village street fair, which raised money for the local memorial hall and meetinghouse.

"In the past they paid between £75 and £100 for public liability cover but this year I don't think I'll be able to place it for under £500," Beaumont said.

"It only raises £3,000 or £4,000 each year so it's a big chunk out of their fundraising.

"I've been placing their business for the past 20 years, without even a hint of a claim."