KFC advert is the most complained-about campaign of all time

The ASA has received 430,000 complaints during its existence, with a record 31,548 in 2011

A Kentucky Fried Chicken ad featuring call-centre workers singing with their mouths full is the most complained-about British campaign in history.

The Advertising Standards Authority (ASA) marked its 50th anniversary by revealing that the 2005 television advert had proved the most offensive in its history, attracting 1,671 complaints.

The majority objected that it could encourage bad manners among children but the watchdog rejected the complaints. Although the advert was "not to everyone's taste", it was unlikely to change children's behaviour or undermine parental authority.

The body has received 431,000 complaints during its existence, with a record 31,548 objections logged in 2011. The increase in complaints was due to an extension of the watchdog's remit into web and social media, the ASA said.

The most offensive campaign of 2011 was a Phones 4 U TV advert which featured a ghost-like girl. The watchdog said that although the ads might cause "unease" among children, they could be shown after 7.30pm. Phones 4 U were responsible for three of the 10 most complained adverts of last year. A promise of "miraculous deals" from a cartoon Jesus Christ was deemed "disrespectful" to Christians during Easter.

"Airbrushing" in cosmetics advertising has become a particular area of public concern. The ASA has banned two L'Oreal ads for foundation and face cream despite issuing new guidance that advertisers shouldn't use digital retouching or products like hair extensions or false eyelashes in a way that could mislead.

Lord Smith of Finsbury, the ASA's chairman, said: "We have to be attuned to changes in society's expectations and attitudes. Where there is growing concern about the glamorisation of violence, or about the impact on children of sexualised images, we need to be prepared to acknowledge these concerns in the way in which we implement our regulatory responsibilities."