Professional indemnity (PI) rates are shooting up by 600% on certain lines of business, according to the managing director of broker Dickson Manchester.

Charles Manchester said premiums had risen by an average of 40% to 50% since the World Trade Centre attacks. But cover for some classes were experiencing sevenfold increases.

"Professional indemnity insurance is up 600% for heavy contractual risks like tunnelling and building bridges," he said.

"No one wants to write them at all, so if you are going to get cover it is very expensive."

Manchester said the PI market had also consolidated, creating less capacity. Last month, AXA Corporate Solutions ceased writing new PI business.

Manchester added that premiums for surveyors, civil and geo-technical engineers are seeing rate rises of "several hundred percent". Highly-exposed actuaries are also experiencing steeper premiums after the collapse of Independent Insurance and Enron.

"There is a greater incidence of claims across the board," said Manchester. "The value of claims in virtually every line of business has increased."

St Paul International Insurance Company's product manager for professions, Jim Gaskin, said PI for architects had also been affected.

"Rises of 30% to 40% minimum are needed," he said.

Manchester blamed a changing culture for the increase in claims.

"People are more litigious and the speed of life is faster now," he said.