Insurance group Aviva said claims from last summer's floods will be £75 million higher than expected.

The company, whose brands inlude Norwich Union, said the bill for adverse weather costs in 2007 now stands at £475 million. Its general insurance business came to the aid of 45,000 households and 6,000 businesses in June and July last year.

The update came as Aviva reported record levels of business in the UK, with life and pension new business sales up 5% to £11.6 billion in 2007.

The weather-related claims have impacted on the group's profitability, underlined by a deterioration in its combined operating ratio.

The key industry measure highlights the amount of money paid out on claims and in costs for every £1 of premiums taken in. Aviva said it expected its ratio to be around 100% in 2007, rather than the 95% it would have achieved if the exceptional weather had not occurred and the 98% own target.

Chief executive Andrew Moss said: 'While our markets will be affected by the current economic uncertainty, I believe we will continue to grow both new business sales and profit in line with our stated targets.'

Shares in Aviva slipped 2% to 597.5p on Wednesday morning.