Britain’s sewers are to be used to deliver ultra-fast broadband to entire cities.

H20 Networks, a Wales-based group, is in talks with councils in Bournemouth, Dundee and Northampton about laying fibre in the sewage network.

It promises, it says, speeds of at least 100 Megabits per second. BT, the country’s main provider, currently offers just 8Mbps.

As broadband has taken off in the UK so too have the variety of services available. But products that enable television and films to be downloaded over the internet are putting an increasing strain on the country’s broadband infrastructure.

The Broadband Stakeholder Group, an industry lobby group, warned recently that Britain risks being left behind other countries if it does not move fast to deploy super-fast fibre networks.

But groups, including BT, have raised concerns about the expense of such an upgrade.

H20 believes that using the country’s sewer network is an ideal solution to the problem. It avoids the inconvenience and disruption of digging-up roads and is ultimately, it says, a cheap way of introducing a super-fast broadband service.

It estimates that it will cost a maximum of £24 million to connect a small city compared with a £80 million cost via traditional routes.

Using the sewers is also, it says, far kinder to the environment than digging up the roads. The group leases space in the sewers from several water companies with whom it has struck deals, including Anglian Water and Scottish Water.

The fibre is fixed into the sewer, lying at depths of up to five metres below the ground.

There is, it claims, no danger of rodents chewing through the fibre.

It is also, it said, in talks with several internet and content groups including Sky, the satellite broadcaster in which News International, owner of Times Online, has a 37.5 per cent stake. A spokesman for Sky said the company does not comment on speculation.

The business, which launched six years ago, already offers a sewer-based broadband service in small areas including Bath and Aberdeen University.

Other countries including France already offer broadband via the sewers. In the UK other groups - such as Urband, a 2002 joint venture between Thames Water and Lattice - have tried and failed with similar schemes.

Proponents of the services said they were simply ahead of their time.