Most motor insurers will produce improved results for 2004 compared to 2003, although many released higher levels of reserves from their claims pots to boost performance figures, according to Deloitte.

Deloitte partner Catherine Barton said: "The headline result disguises a downturn in underlying performance. In 2004 many firms chose to release money from their prior year reserves, allowing them to continue to defer or defy a visible downturn in the cycle for one more year."

She said this may have been due to the impact of the Courts Act being milder than expected, a less rife compensation culture or that insurers simply wanted to show better topline results.

Barton added that insurers were cutting rates tactically.

"This year's results are reflecting a range of influences on performance, but we believe the market will remain stable," she added.

' Standard & Poor's is to release its motor insurance market analysis this week.