CNA's London-based commercial and marine operations cost it $69m (£48m) and was part of a $1.6bn (£1.12bn) group loss last year.
The US insurer took the sum as an after-tax charge on its fourth quarter results thus boosting reserves in its UK direct insurance operation for the current year.
An additional $160m (£112m) was also taken in the same quarter as the cost of increasing reserves for the previous underwriting year for CNA Re.
CNA Re is a London-based reinsurance operation, which was put up for sale in August last year. The group has yet to find a buyer.
It has ceased underwriting in London where it has about 75 staff, but business is still being written under the CNA Re name from Chicago, the group's base.
Chief executive Bernard L Hengesbaugh said: "2001 was the year when we stepped up to a series of tough issues. Now it's time for us to deliver."
Hosted by comedian and actor Tom Allen, 34 Gold, 23 Silver and 22 Bronze awards were handed out across an amazing 34 categories recognising brilliance and innovation right across the breadth of UK general insurance.
