Royal & Sun Alliance says its profits had trebled in the first three months of 2005 as benefits flowed from its restructuring programme.
The UK's second largest insurer, which operates the More Than brand, said pretax profits totalled £122 million in the first quarter, compared with £ 44 million a year earlier.
The improvement was led by its core markets of the UK, Scandinavia and Canada and came despite further losses in the United States, where it has been hit by asbestos claims and compensation payments.
R&SA said its operating result for the quarter, which includes forecasts for investment returns, was £160 million - up 95 per cent on a year earlier.
The combined operating ratio (COR) from ongoing business - a key industry measure of profitability - improved to 91.2 per cent in the three months from 94.2 per cent at the same stage of 2004.
COR, which represents the amount of money spent paying out on claims and in costs for every £1 of premiums taken, improved in the UK to 94.3 per cent from 98.2 per cent, following "strong results" in personal and commercial insurance.
R& SA said underlying claims on property improved despite losing £24 million in payouts for storm damage, including the January floods in Carlisle. Underwriting profits in the UK rose steeply from £2 million to £33 million.
More than £200 million in annual savings have been generated since R& SA embarked on a radical overhaul in 2003, including a £960 million rights issue.
The group has now cut its headcount on both sides of the Atlantic and has also taken steps to reduce its exposure to risk in the United States, where it recorded an underwriting loss of £651 million two years ago.
Chief executive Andy Haste - the former boss of AXA Sun Life - said the group remained confident of reaching its goal of £ 270 million in annual savings.
The breakdown of the figures show that profits from its UK, Scandinavian and international businesses jumped to £145 million from £83 million.
But losses of £23 million in the United States restrained progress.
Royal & Sun is the first UK insurer to report under new IFRS accounting rules.
Mr Haste said the results reflected a focus on profitable business at a time when insurance rates were falling in some areas, such as UK commercial risks.
"This is a strong start to the year from all our core markets in what is a competitive market," said Mr Haste, adding that the group was on track to attain its cost and underwriting targets for 2005 and saw the industry's first-quarter pricing trends continuing.
Meanwhile Axa, France's biggest insurer, with extensive UK interests, reported higher sales in the first quarter at its life and savings arm, partly on strong unit-linked sales.
They rose 12 per cent to 1.263 billion euros (£865 million).
On a comparable basis, stripping out changes in currency and corporate structure, sales jumped eight per cent.
Axa's property and casualty revenues rose five per cent on a reported basis to 5.903 billion euros (£4 billion), as solid pricing and moderate portfolio growth lifted personal and commercial lines.
Royal & Alliance shares yesterday closed at 771/2p up 4p.