The stakes were raised in the billion-pound battle over pleural plaques this week when the Court of Appeal ruled that the asbestos-related condition was not compensateable.

But claimant lawyers have vowed to take the case to the House of Lords, leaving the question of whether sufferers can claim compensation yet to be finalised.

According to legal experts, there is a danger that the highest court in the land will overturn the decision, leaving insurers facing potentially even higher exposures than the estimated £25m a year these claims currently cost them.

Pleural plaques are symptomless, have no adverse effect on any bodily function and, being internal, have no effect on appearance.

Claims are currently capped at £3,500 for a provisional damages and £6,000 for a final award, but all three Court of Appeal judges ruled that these levels were too low.

Toby Scott, industrial disease expert at law firm Eversheds, said: "The judges were unanimous in finding that if compensation had been payable it would have been paid not at the reduced levels announced in last year's test case but at the original and higher levels."

Dominic Clayden, Norwich Union's technical claims director said: "We welcome the judgment and believe it to be a pragmatic result on the issue of compensation being awarded for an asymptomatic condition.

"The issue of compensating claimants with serious asbestos-related conditions or who suffer from impairment as a result of exposure to asbestos has never been in question and they will continue to receive compensation."

The Lords' decision is final.