Financial strength ratings of R&SA, Zurich and Equitas are not likely to be affected by new research showing UK asbestos claims will cost up to £20bn.

A report by the Actuarial Profession (a combination of the Institute of Actuaries and the Faculty of Actuaries) said claims would be £8bn-£20bn over the next 30 years and that UK insur-ers could expect to pay out up to £10bn.

But AM Best said that the figures were in line with those currently used to assess financial strength.

AM Best European operations managing director Stuart Shipperlee said pockets of exposure within the figures could cause ratings movements and that asbestos exposures would be a drag on earnings for the next 15 years.

' A test case to stop claims for pleural plaques will be fought next week by Norwich Union.

It is understood that pleural plaques do not exhibit symptoms and awards are currently £10,000 per claim plus costs.

Experts say that there are thousands of claims per year for pleural plaques and that this figure could be maintained for the next 20 years.