A controversial poster featuring model Sophie Dahl in a suggestive pose accounted for a third of all complaints about billboard ads last year.

Almost 1,000 people wrote to object about the advert for Yves Saint Laurent's Opium perfume, according to the Advertising Standards Agency.

And a number of other sexually provocative ads also caused widespread offence.

The perfume poster featuring Sophie Dahl was the most complained about advert in the past five years, said the ASA's annual report.

The posters were banned after the ASA ruled they were offensive and degrading to women.

The authority received more than 12,000 complaints last year.

Redheads offended

The second most complained about advert was for gas supplier Npower, which featured a ginger-haired family and the words `There are some things in life you can't choose'.

The ASA received more than 200 complaints from people who believed the advert was offensive to redheads, but the authority ruled they were not justified.

Sexually explicit

Objections to posters for underwear firm Gossard were upheld for being sexually explicit, and they were ordered to be removed.

Complaints were up by over 4% compared with 1999, although the number of adverts complained about fell from 8,617 to 8,547.

The ASA said that almost 30% of complaints last year concerned taste and decency.