Escapees in the biggest prison break-out in UK history planned to take flight again during their trial, police intelligence suggested.

The IRA believed there were two options for the men escaping from a jail where they were being held during court proceedings in North Belfast, according to records from 1987 disclosed by the Northern Ireland Office.

However, former Lord Chief Justice Sir Robert Lowry vetoed proposals to handcuff senior republican Gerry Kelly and 15 other IRA men during their 1987 trial for fleeing the high-security Maze Prison in Northern Ireland.

One warder was killed and another seriously injured as dozens of inmates forced their way from the compound.

A director of prison security wrote: "As this is likely to be the final phase of the trial, the prisoners may well seek to make an escape attempt and there is some intelligence to that effect.

"Consequently I take the view that returning them (other than Mr Kelly and one other) to HMP Maze at weekends would be a sensible additional precaution, partly because Maze is inherently more secure than Belfast and partly to make the planning of an escape more difficult."

The Maze housed some of Northern Ireland's most notorious paramilitary prisoners during the Troubles.

Mr Kelly, now a senior member of Sinn Fein who represents North Belfast in the Stormont Assembly, had been jailed for life in 1973 for the Old Bailey and Scotland Yard bombings.

He was among 38 IRA inmates who fled the Maze in Co Antrim in September 1983. They used smuggled guns and knives to overpower prison staff before hijacking a food lorry and driving to the main gate.

Some were subsequently recaptured - Mr Kelly in Amsterdam - and returned for trial at Crumlin Road Courthouse in Belfast, which was connected to HMP Belfast (now Crumlin Road Gaol) by an underground tunnel.

Most of the inmates were returned to the Maze for detention during weekends amid the lengthy trial - extra security measures had been taken following the earlier escape.

But Mr Kelly was not returned to the Maze during his trial for reasons surrounding his detention, the records said.

Files from 1987 released by the Public Records Office Northern Ireland disclosed that the Army and RUC were asked to increase their patrols near the courthouse and Crumlin Road Gaol, while special vigilance was exercised by police inside the courthouse searching visitors.

Inmates were strip-searched before appearing in court each day.

The director wrote: "The Lord Chief Justice Lowry would not however consent to our proposal to handcuff the prisoners in the court as he considered that both the prison and police authorities would take adequate steps to ensure the safe custody of the prisoners without this being necessary."