The cost of crimes against British small and medium-sized companies totalled at least £722m in 2005, according to research by AXA.

But under-claiming by companies meant the true cost was probably much higher, the insurer added.

Theft was the biggest problem, accounting for 45% of all claims, followed by arson at 42%.

Malicious damage was the third most common crime acounting for 12% of claims, the survey found.

Overall, crime claims by firms rose by 27% in the last quarter of 2005.

According to AXA, Derby was the worst city in Britain for crimes against businesses.

In the third quarter of 2005, 31% of claims from Derby firms during that period were related to crime.

Bradford was the second most crime-ridden area with 30% of claims relating to crime, followed by Nottingham on 29% and Cardiff on 27%.

Neil Mercier, property insurance manager at AXA, said: "The findings demonstrate just how much of a problem crime is for small and medium-sized businesses."