Three national newspapers have defied a request to censor an advertisement about abused children deemed "too shocking" for publication.

The Committee of Advertising Practice issued notices to publications advising them not to run the Barnardo's advert showing a baby who had injected itself with heroin.

But the full page picture was printed in Saturday's Independent, Guardian and Scotsman newspapers, while several Sunday papers were expected to follow suit.

Barnardo's said the Daily Mail, the only other paper which had received a booking for the advert, declined to accept it on grounds of decency.

The CAP, the division of the Advertising Standards Agency that deals with self-regulation, said it had already begun receiving complaints from readers.

It asked the newspapers not to run the advert again.

A CAP spokesman said: "We know papers may not have had time to withdraw the ad after our plea, because of production timetables, but we ask them not to do so in the future.

"People should think twice before accepting this ad. Children are one of the most sensitive subjects, and so are drugs."

The advertisement aims to show what can happen to abused or disadvantaged children unless they receive help from charities such as Barnardo's.

Text accompanying the image reads: "John Donaldson. Age 23. Battered as a child, it was always possible that John would turn to drugs. With Barnardo's help, child abuse need not lead to an empty future."

The image is part of a wider, hard-hitting campaign which also includes adult images of young children living on the streets, on the brink of suicide or in prison.

Barnardo's spokesman Andrew Nebel said: "The basic premise of the entire campaign is centred on Barnardo's work with children and young people to prevent them experiencing the negative situations shown in the advertising."

Mr Nebel said the advert, the fifth in this campaign, was carefully planned and considered before it was produced.

"At no time did our findings give us cause for concern that our audience found it unduly shocking or distressing.

"We are not a commercial organisation that is spuriously attracting attention to shift goods off shop shelves, we are a charity trying to raise awareness of our work, all of which aims to create better and different futures for today's children and young people," he said.

Editors of the newspapers defended their decisions to publish, saying the advert's message was harsh, but clear.

Alan Rusbridger, editor of The Guardian, said: "It is shocking but it is the sort of image that Guardian readers are sophisticated enough to deal with, and understand its message."

Roger Alton, editor of The Observer newspaper, said: "There are staggering problems of drug abuse and child abuse within families.

"Anything that wakes people up to this is for the better. People sit around with their heads in the sand too often. I think shock adverts can be very good."