Broadband companies that obstruct consumers wanting to switch to a new provider will risk a hefty fine, under new rules unveiled by the regulator yesterday.

Ofcom is to introduce in February new regulations aimed at ending the frustration endured by some of Britain’s 11.5 million broadband households seeking to switch internet supplier. Companies that breach the rules face sanctions including a fine of up to 10 per cent of annual turnover.

However, consumer groups complained that the rules — which do not cover cable broadband providers and only partly cover local loop unbundling services such as Carphone Warehouse’s TalkTalk “free” broadband — do not go far enough.

The change was prompted by thousands of complaints from customers to the regulator. Under the new rules, broadband providers will be forced to comply with customer requests, supplying free of charge the necessary migration authorisation code (MAC) on request.

The company will not be able to withhold the code — a unique reference that enables customers to switch smoothly and with minimal disruption — even if a customer owes money. Problems around the MAC code are deemed one of the biggest threats to the continued competitiveness of the UK’s broadband market.

Ofcom fears that customers may be prevented from enjoying the plethora of new services that offer faster speeds at cheaper prices if such obstacles are not removed.

Although a code of practice exists, making broadband switching easier, many companies have not signed up and Ofcom has no powers to punish offenders.

Orange recently started to charge for second requests of a MAC.

Under the rules, wholesale broadband providers will also be forced to provide MAC codes.

The regulator is also to consult on alternative ways of providing a MAC code, which, at present, can be secured only from a company’s existing broadband provider.

USwitch, the independent price comparison service, said that the plans did not go far enough. Steve Weller, head of communications, said: “The most crucial matter, that Ofcom has failed to address today, is how MAC codes can be successfully transferred from one Local Loop Unbundled [LLU] provider to another.”