Fortis Insurance's motor book saw premium volumes fall in the second quarter of 2005 due to pressure from direct insurers.
The company reported a 5% drop in GWP in its motor portfolio to £190m from £200m in the second quarter of 2004.
But the company said it "continues to outperform in terms of underwriting performance and expense management".
In contrast, the insurer's household, SME commercial and travel books showed growth in the second quarter of 2005.
Household GWP increased by 7% compared to the second quarter last year, aided by the roll-out of House Guard Extra.
Travel saw substantial gains, with an overall GWP year-on-year increase of 49% to £23m, while the SME commercial division picked up 14% in volume to £29m.
Overall GWP increased by 1% from £294m in the second quarter of 2004 to £297m in the same period in 2005.
Chief executive Barry Smith said the results were due to "quality underwriting and active expense management" and said he was committed to helping the intermediated market succeed.
The international Fortis group reported a net profit of €684m (£467m) for the first half of 2005, 21% up on the €564m (£385m) declared for the first half of 2004.
Non-life GWP increased by 2% to €2.7bn (£1.8bn), while the combined ratio improved by 4% to 94% for the half-year.
