BT is launching a "breakthrough" new service aimed at stopping one of the "great annoyances of modern life:" nuisance calls.

Most people endure an unwanted telephone call at least once month, mainly about PPI or personal injury claims, automated marketing messages or sales.

But now a team from the telecoms giant will monitor calls to the company's ten million domestic customers and identify any patterns of callers.

The "rogue" numbers will be diverted to a junk voicebox, which BT estimates will affect up to 25 million unwanted calls a week.

BT customers will also be able to divert calls themselves to the "blacklist".

They say the service, believed to be the first of its kind, will be launched later this year, harnessing huge computer power to analyse data.

John Petter, chief executive of BT Consumer, said: