LONDON (Reuters) - The advertising watchdog on Wednesday upheld complaints that images used to promote an action film glamorized guns amid growing public concern about youth violence.

The Advertising Standards Authority (ASA) said it backed 55 people who complained about posters for the thriller "Shoot 'Em Up."

One of the ads showed actor Paul Giamatti pointing a gun while holding a mobile phone with text saying "Just another family man making a living."

Another depicted actor Clive Owen jumping in the air holding a pistol in each hand which he was pointing toward the viewer.

A London-based community safety group complained, saying the ads glorified gun crime.

The ads attracted complaints from people who said they were offensive and insensitive to those who had been affected by gun crime, citing the family of Rhys Jones, an 11-year-old boy who was shot dead on a street in Liverpool.

His death, which followed a wave of teenage murders involving guns, horrified the country and prompted Prime Minister Gordon Brown to promise action to tackle the issue.

Entertainment Film Distributors, which made the posters, said it did not believe they glamorized gun violence. It said they had been specifically designed so the guns Owen was holding were angled away from the viewer.

But the ASA, in explaining its ruling that the ads should not be used again, said it was mindful of growing public concern. Whilst it did not uphold complaints relating to Jones's death, it did back the views of the community group.

"We concluded that (the) ads could be seen to condone violence by glorifying or glamorizing the use of guns."

Earlier this week the ASA reported that there had been a sharp rise this year in complaints from the public about advertisements that depict or allude to violence.

So far this year it has received 1,748 complaints about 523 ads, compared with just 1,054 complaints received in the whole of 2006 about 254 ads.

"The ASA takes the increase in complaints very seriously and is keen to hear the public's views," said Lord Smith, Chairman of the ASA. "Our key priority is how we ensure children are protected from harmful images."

The ASA is holding a seminar on Wednesday to discuss the issue through debates focusing on the depiction of guns and knives, horror films, video games and general violence.