Reinsurer Equitas warned it may have to increase its reserves against asbestos claims for the fourth time in five years, revealed a report. It issued the warning as part of its first half results.

Having continued to monitor its asbestos exposure, Equitas said: "It may be necessary to increase asbestos reserves at the year-end following our detailed review.

"The group is disappointed though not surprised, that progress in the United States Congress toward asbestos reform legislation has been slow."

Equitas chairman Hugh Stevenson said: "Even in this environment, we have pursued opportunities to reduce our outstanding asbestos liabilities by closing asbestos claims on acceptable terms."

A further strengthening of asbestos reserves would follow the addition of £399m to the reserves in March this year, said the report. That took the total reserve to £3.7bn.