Thomson, which was owned by Dun & Bradstreet of the US and Thomson Corporation of Canada, published the first Yellow Pages for the Post Office in 1966 but started producing its own local directories with Dun & Bradstreet in 1981.
Richard Callahan, president of US West International, said the acquisition was an important part of the group's efforts to develop multimedia services in the UK. US West already owns half of Telewest, the largest cable television company in Britain.
The company is also an equal partner with Cable and Wireless in Mercury One-2-One, the mobile telephone service launched last year.
The directory advertising market in the UK is worth up to pounds 800m but is underdeveloped, Mr Callahan said. He plans to build on Thomson's existing business, which involves the publication of 155 local business directories reaching 80 per cent of the population.
In future customers may be able to dial into a database for information on advertisers. Ultimately the directories may be produced in electronic format.
Thomson Directories, which employs 800 people, has a turnover of pounds 50m a year but does not disclose profits.
BT also declines to disclose figures for its Yellow Pages business but says that it is showing good growth.
US West publishes 300 separate directories in the 14 western and mid-western states in the US where it offers telephone services. The group has also started publishing directories in Poland.