There is no evidence that trials have been prejudiced and the media is well aware of its responsibilities

Bob Satchwell - Society of Editors

Lord Irvine said existing self-regulation under the Press Complaints Commission may not offer enough protection.

"Payments made to witnesses for their stories by the media are objectionable, and even more so where they are conditional on the conviction of the accused," he said.

"Payments create a real risk of encouraging witnesses to exaggerate their evidence in court so as to make it more newsworthy, or to withhold relevant evidence from the court in order to give newspapers exclusive coverage later on."

He said juries may also be concerned about the validity of evidence if they know a witness is in touch with the media.

The new rules could also affect the offer of cash rewards for information.

Baroness Scotland said there was "real concern" after the judge in the Damilola Taylor murder trial threw out evidence from the prosecution's chief witness. It was claimed a �50,000 Daily Mail reward could have acted as "inducement" to the 14-year-old girl.

Cost to taxpayers

Lord Irvine said newspapers whose actions lead to the collapse of court cases could be forced to pay millions of pounds in costs.

In the Leeds case the taxpayer is thought to be facing a bill of up to �8m.

Baroness Scotland said: "A trial's abandonment not only seriously affects the administration of justice, it can prove to be very expensive for the taxpayer."

She said the power would be used "sparingly" but newspapers or broadcasters could expect to be punished if an "unnecessary or improper act" forced the a trial to be abandoned.

'Sledgehammers'

The ban on payments to witnesses was questioned by the Society of Editors, which said such a move would be counter-productive.

Glitter case led to calls for press regulation

Its executive director Bob Satchwell said: "On the rare occasions that this becomes an issue governments threaten to bring out their sledgehammers.

"There is no evidence that trials have been prejudiced and the media is well aware of its responsibilities to the administration of justice."

Mr Satchwell said it was patronising to juries to suggest they could not take into account any payments being made and the effects that could have.

Commenting on the possible effect on reward money he said: "The offer of rewards for information leading to a conviction has long been an effective aid to justice, usually with the active encouragement of the police.

"Does this mean rewards, part of justice since history began, are to be abandoned?"

Evidence 'doubted'

Plans to outlaw "chequebook journalism" were floated in the 1990s, after the trials of Rosemary West and Gary Glitter.

During their trials defence lawyers cast doubt on witnesses' evidence because of payments they'd been promised by the media.

The Press Complaints Commission tightened up its voluntary code, but the Lord Chancellor says that's not stopped newspapers paying witnesses and a new law is needed.