The UK's big two cable communications operators are to join forces in a drive to promote the take-up of broadband internet services, BBC News Online has learned.

Cable firms NTL and Telewest will on Monday unveil a joint marketing campaign, named Building Broadband Britain, to accelerate the spread of high-speed internet services through Britain, a source has revealed.

The deal follows concerns among MPs, industry and consumer groups over the slow take-up in the UK of broadband internet services, a market in which former state operator British Telecom has retained control despite efforts by the government and watchdogs to boost competition.

Two weeks ago, watchdog Oftel ordered BT to give rival operators cheaper access to the telecoms' giant exchange network, in an attempt to entice competitors into the market.

NTL and Telewest are offering broadband internet connection �24.99 a month, compared with the �40 a month for the equivalent BT service.

But it is not known yet how many homes will be able to plug their PCs into an NTL or Telewest broadband feed.

The operators' networks bypass only about 16 million homes, about two thirds of the UK total, and many of those would not be able to use cables for internet use until system improvements are made.

'Natural medium'

NTL declined on Sunday to comment on the Building Broadband Britain campaign.

But a company spokeswoman confirmed NTL's commitment to high-speed internet services.

"We were talking about this as long ago as 1993," the spokeswoman told BBC News Online.

"Anyone who has used a broadband internet service will recognise the advantage is has over normal connection. And we believe cable is the natural medium for broadband."

The firm has spent an average of �1m a day over the last eight years rolling out its cable network, she added.

The tie-up with Telewest comes two months after NTL sealed an alliance with Orange over the sharing of mobile phone and cable services.