The rules form part of the industry's code of practice administered by the Press Complaints Commission (PCC), whose chairman, Lord Wakeham, yesterday spoke out against the recent "stream of injudicious stories centring on the private lives of public individuals".
Grahame Thomson, secretary of the editors' committee which updates the code, confirmed last night that the publication of pictures from the faked video of Princess Diana and her former lover, James Hewitt - published by the Sun on Tuesday as the real thing - raised privacy issues.
That section of the code was being "restated", he said. "There has to be a limit as to how far you go. If a paper is stupid enough to accept phony material without checking, that is up to them.
"But the protection of privacy is very important, and although there is fairly adequate cover in the code, we are making some changes."
The issue of media misbehaviour has returned to the fore following several recent "exclusives" about members and former members of the Royal Family, including the revelations of a fortune teller consulted by the Duchess of York, and a claim that Prince William had a crush on the step-sister of one of his schoolmates.
Neither story triggered any complaint to the PCC, while the Sun's five- page "Royal World Exclusive" about the Diana hoax video prompted only four complaints, all from members of the public.
As part of a general clampdown, however, the Lord Chancellor's department is expected to issue a consultation paper later this month recommending that media payment of huge sums to witnesses in trials beoutlawed.
The move, triggered by the buy-ups of witnesses in Rosemary West's trial for murder last year, signals the Government's lack of confidence in newspapers' attempts at self-regulation.
The Code of Practice says that "intrusions or enquiries into an individual's private life without his or her consent . . . are not generally acceptable" unless in the public interest.
Another section, also being revised by the editors' code committee, says that payments should not be made to potential witnesses in court cases without the same justification.
Yesterday Virginia Bottomley, the Secretary of State for Heritage, said she believed there was room for tighter safeguards on the press but that legislating would be "fraught with difficulty".
"Legislation tends to be costly, complex and does not necessarily deliver results," she warned. But she emphasised that she took the question of privacy "extremely seriously" and that it would remain under review.
Earlier this year she asked Lord Wakeham to ensure that commitments on self- regulation were being taken forward. These included writing the code into contracts of employment, getting more lay members on the PCC, and setting up a public hotline to make the commission more accessible.
"There is room for further tightening the safeguards," Mrs Bottomley said. "It is the dilemma in a modern democracy in a multi-media age that you have to temper freedom of information with responsibilities."
But Jack Cunningham, Labour's Heritage spokesman, said: "Without a strengthened Press Complaints Commission we will see some sections of the press continue with their deplorable behaviour, with its inevitable damage to people's lives and privacy."
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