Most insurers and reinsurers are unintentionally covering their policyholders for cyber risks, according to insurance agency Inwebsure.

At the ICMIF conference in Athens, Inwebsure chief executive Amnon Pelz said most insurers and reinsurers were liable for damage caused by hackers, viruses and illegal copyright.

"There are a lot of problems regarding cyberinsurance," he said. "In some cases the insurance market can get it in the back door without meaning to cover it."

Pelz urged the market to use exclusion clauses in all policies to prevent unintentionally covering the risk. But he added that insurers and reinsurers should be extra vigilant as they could be subject to cyber problems themselves.

He said as an example, electronic signatures used to validate documents online might be used by hackers.

Pelz said the problem was likely to increase as companies relied increasingly on modern technology to do business. He said there were now an estimated 30 million registered domain names.

"This offers enormous advantages to business development, but is also fraught with the risk of tremendous loss," he said.

Inwebsure has launched a cyber insurance product globally to cover these risks. Premiums start from $1 (69p) a day, depending on the size of the website and the volume of email users protected.

The policy has been piloted in Israel since

1 January and more than 100 companies are now insured. It is underwritten by Israeli Phoenix Insurance Company and reinsured by Swiss Re.