Lord Archer could be returned to a closed prison after he attended a party held by a former Conservative Party colleague while on a home visit.

Archer has been banned from leaving the open prison in Lincolnshire where he is serving a sentence for perjury while the Prison Service carries out an investigation.

Archer and his wife, Mary, went to the home of former education and employment minister Gillian Shephard reportedly without informing authorities at the jail.

Martin Narey, the director general of the Prison Service, said: "The allegations are serious and, if true, constitute a serious breach of trust which may result in Lord Archer's return to a closed prison."

'Naturally assumed'

In a statement Mrs Shephard, the MP for south-west Norfolk, said: "We gave a small party for friends at our home in Norfolk ten days ago. Mary and Jeffrey Archer were invited.

"When they accepted, I naturally assumed that the terms of Jeffrey's conditions to leave from prison permitted him to attend the event.

"If they did not, that is a matter for Jeffrey and the Prison Service to sort out."

The 62-year-old former deputy chairman of the Conservative Party is currently serving a four-year sentence at North Sea Camp open prison.

He was jailed at the Old Bailey in July last year after being found guilty of perverting the course of justice and lying in his 1987 libel trial against the Daily Star newspaper.

The best-selling novelist's move to the open prison has allowed him a greater degree of freedom and he is allowed home visits as well as time out to work at Lincoln's Theatre Royal.

Lords ban

Separately it recently emerged that Archer could be expelled from the House of Lords under proposed new rules.

The Lord Chancellor, Lord Irvine, is expected to receive the recommendation as part of a report from an all-party committee of MPs and peers which he set up to consider reforms for the Upper House.

One proposal is that any peer sentenced to a prison term of more than 12 months should be automatically disqualified from membership of the House of Lords.

Archer would almost certainly be caught by this new rule if it were adopted.

It would put the House of Lords broadly in line with the House of Commons, where an MP convicted of a serious offence is automatically disqualified.