Journalists who pay witnesses involved in criminal trials face jail under laws proposed by the Lord Chancellor.
The practice of "cheque-book" journalism, where witnesses are given money for their stories, will be outlawed under the reforms to be announced this Tuesday.
The proposals form the basis of a consultation paper also criticising media rewards as an incentive to witnesses.
Judges are increasingly concerned that witnesses are holding back evidence for newspapers or exaggerating details in court to command a higher price for their story.
Last week, the judge in the Damilola Taylor trial threw out the evidence of one of the prosecution's chief witnesses. Mr Justice Hooper said a £50,000 reward offered by the Daily Mail acted as an "inducement" to the girl, aged 14.
And the judge trying the teacher Amy Gehring called three schoolboys back to the witness box after claims that national papers had offered them thousands of pounds for their stories. Ms Gehring was cleared of four counts of indecent assault against boys.
Judges will have new powers to prosecute anyone who agrees to pay, or hands over money to, a witness in the run-up to or during a criminal trial.
Editors will be unable to use the defence that paying a witness money has not prejudiced a trial. However, they will be able to argue they were unaware the person they approached before a trial was to be a witness.
Until now, the media has been restricted only by a Press Complaints Commission voluntary code, which says writers should not pay witnesses involved in current criminal proceedings unless there is a public interest, and that any offer should be disclosed to the court.
Pressure to outlaw "cheque-book" journalism grew after the Rose West trial in 1995 when it emerged that prosecution witnesses had been paid by newspapers. Last year, the Lord Chancellor said he would draw up proposals for a review of the issue.Reuse content