Social networking site Facebook has introduced a feature that gives advertisers the option not to appear on specified pages.

Last week Vodafone pulled adverts from Facebook when they appeared alongside the profiles of the British National Party (BNP).

The debacle sparked an exodus of advertisers from the site, including Virgin Media, First Direct, Halifax, the AA and the Central Office of Information, which coordinates government advertising.

All the groups said that until it could be assured that their ads would not appear alongside material that violated their particular company policies, they would not be running campaigns on Facebook.

The new feature is Facebook's solution to the issue.

There has been growing concern from advertising and marketing agencies about buying space on social networking websites due the random nature of which page their ad might be shown on.

Facebook's move has been backed by ISBA, a representative body for over 400 leading UK advertisers.

"Today's Facebook announcement ... looks encouragingly like a solution advertisers can work with," said Bob Wootton, media and advertising director for ISBA.

"Advertisers will ... hope that Facebook will go on to set a new standard in online brand protection that will become the benchmark to which other site owners will aspire."

Facebook has said the blocking feature will be offered to international advertisers at a later date.