Terrestrial television companies are governed by guidelines, rather than rules, when it comes to violent images they can transmit including news broadcasts. The more grisly images are not generally shown before the Nine O'Clock News on BBC1 and ITN's News at Ten.

"Essentially, we expect the editors of news programmes to use their judgement," says an ITC spokesman. "With regard to any pictures with the potential to cause distress, we would expect them to bear in mind the time of the broadcast. Those more explicit images of violence or distress, we would expect to be shown after the 9pm watershed"

Anne Weir, of ITN, says this responsibility is taken very seriously. "We are very aware of the age of our audience at the various times of a news bulletins. In 1994 we had pictures from Rwanda of dead bodies floating down the river. We showed those on News at Ten and would not have shown them any earlier."

James Boyle, chief advisor of editorial policy at the BBC, says: "One of our criteria relates to emotive behaviour, which has particular significance to children. Our news footage is edited in a particular way in order to avoid this happening. We also look at the balance between the demands of the truth and the danger of desensitising. Shock is a part of understanding, but overuse of that can be counter-productive."

Sky Television has a 24-hour news operation and rules which could mean more grisly images are shown earlier in the day. A spokesperson for Sky News says: "It's a constant process of adjustment, checking that information is accurate and not unduly distressing. We are not immune to watershed considerations, but are very committed to the urgency of delivering the news."