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."
