Jailed author Jeffrey Archer could face disciplinary action if his new diary detailing his time behind bars breaks strict rules regarding prison writing.
Publisher Macmillan revealed the millionaire novelist's latest book - A Prison Diary- would describe life inside London's Belmarsh Jail, where he served the first three weeks of his four-year sentence for perjury.
The publisher said Archer had decided to write the volume as a way of keeping himself sane while locked up.
But a spokesman for the Prisons Service says if the infamous inmate had not followed strict rules regarding prison writing he could be in for an even longer sentence.
The spokesman said the Prison Service had not seen the book but if Lord Archer identified any other prisoner, described his or any other prisoner's crime or been paid for his work his term could be extended.
"The Prison Service can confirm that if Lord Archer has broken any of these rules he may be opening himself up to disciplinary action, which could lead to added days being put on his custodial sentence," he said.
According to the Daily Mail, Archer refers to Great Train Robber Ronnie Biggs and Jill Dando's killer Barry George in the diary, which could break one of the rules.
Macmillan said Archer had not received an advance for the diary and had instructed that the payment for serialisation be donated to drug rehabilitation and victim support groups.
Mr Richard Charkin, chief executive of Macmillan, predicted that Archer would earn about stg£200,000-300,000 in royalties from the book.
Meanwhile Edwina Currie hit back at barbed comments made by Lady Archer who this week suggested that ex-premier John Major had suffered a lapse in taste in conducting an affair with the former Tory minister.
Mrs Currie, who studied chemistry with Lady Archer at Oxford University, said: "When Mary went off with this little runt ... called Jeffrey Archer who couldn't even get into ... he had no O-levels or A-levels.
"He lied through his teeth - that's what he's serving his jail sentence for now - perjury.
"When she went off with him we couldn't figure out what on earth she saw in him," she told BBC Radio Derby.
PA