Firms must set up processes to renew domain names and guard against Web site hijackers, or their businesses may suffer, say experts. More than 1,500 domains owned by ordinary firms six months ago are now registered by pornographers, according to Internet management specialist Websense.

Barbara Cookson, a partner at law firm Nabarro Nathanson, said, "In most cases missing the renewal is simply down to poor administration." She warned that Internet scanning tools can rapidly grab newly available names.

In March, the Poetry Society lost money when its Poetrysoc.com domain - and its 300,000 hits per month - was grabbed by a betting firm.

Firms should set up a renewal prompt system and not rely on ISPs to register domains, said Cookson.

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