Premiums for employers' liability and public liability insurance have doubled over the past year alone, BRIT Insurance Holdings reported.
The liability classes show by far the highest rate increases the group has achieved since last year although casualty rates had increased by 65% and general aviation by 50%.
Of 11 classes of business, only airline cover had decreased. Prices fell by 10% over the period.
BRIT today issued a trading statement saying it had experienced "exceptionally positive" renewals so far this year.
Chief executive Neil Eckert said: "We have already achieved the goals we set ourselves at the time of our recent fundraising, placing us in a strong trading position for 2003.
"Brit has established itself as a major force in the London Market. We are delighted with Brit Insurance Limited's recent upgrading by A.M. Best, especially as it is one of the few insurance companies to have been upgraded in the last 12 months."
