The Prime Minister told the Conservative Central Council in Harrogate, North Yorkshire, that he did not favour censorship.
But he added: 'There is too much violence on videos and television. We can say to parents: control what your children watch. And we can say to those who make and distribute films and videos: think whether a relentless diet of violence won't have a serious effect on the young. And we can say to television programmers: don't just be careful when you show it - be careful what you show.'
One party source said yesterday that some senior Tories believed that the problem of screen violence and its links with crime had been overlooked because debate had concentrated on the separate issue of pornography.
Mr Major was speaking after Alan Yentob, Controller of BBC 1, had admitted that it was wrong to screen an episode of the hospital drama Casualty that featured teenage violence and arson. Mr Yentob told Channel 4's Right to Reply programme: 'In future we shall take more care and scrutiny to ensure we understand public sentiments and climate.'
But 'if you make drama serials of the quality of Casualty, you have to be able to engage in issues that affect society'.
Mary Whitehouse, president of the National Viewers' and Listeners' Association said: 'It's very unusual for someone in Mr Yentob's position to apologise, but it's not good enough just to say sorry.'
John Willis, Director of Programmes for Channel 4, said the channel had 'a clear policy of not broadcasting gratuitous violence'.
The Prime Minister's speech echoed views expressed recently by Hollywood actors. Sir Anthony Hopkins said last week that he may not take part in the sequel to Silence of the Lambs, in which he played Hannibal Lecter, a cannibal and serial killer. Sir Anthony said: 'We've seen some awful things in Britain recently. We must all think very carefully about the films we make.'
Jack Nicholson said: 'I think films should inform you about life, not just show violence. I worry about where movies are going.'
In his speech yesterday, Mr Major defended his recent remark on crime that 'we need to understand less and to condemn a little more'. He said: 'Unless society sets rules and standards and enforces them, we cannot be surprised if others flout them.'
Labour's leader, John Smith, speaking in Scarborough, countered: 'Instead of condemning and wringing his hands, it's time he took action to tackle this deep and serious problem.'
Mr Major's denunciation of screen violence came as Kenneth Clarke, the Home Secretary, promised new criminal justice measures. These would include new police powers to impound the cars - and 'other property' - of would-be 'ravers'. Police would be able to turn back crowds suspected of travelling to 'raves' - the unlawful mass teenage parties which caused outrage in rural areas last summer.
'Peaceful rural communities must not become the dustbins for the excesses of city life,' Mr Clarke said.
There would also be fresh curbs on those who committed crime while on bail, he added. Police would be given more powers to challenge bail applications and magistrates would be able to hand down stiffer sentences to those on bail. Legislation on joy- riding - already announced - would increase the penalty for causing death by dangerous driving from five to 10 years.
Last week Mr Clarke promised legislation to allow persistent teenage offenders to be detained in secure approved schools.
Real Life, page 20