Extraordinary plans to redraw the Irish Border - which included handing over west Belfast to the Republic - were seriously considered by British officials in the 1980s, according to previously classified state papers released today.

The radical proposals - which reached the desk of Britain's prime minister Margaret Thatcher - also suggested ceding most of Derry city to the Republic.

A briefing paper prepared by officials at the Northern Ireland Office (NIO), based on a new partition plan put forward by an academic, suggested slicing Northern Ireland in half and cutting its population by 500,000.

It also mentioned establishing a "walled ghetto" in west Belfast.

However, officials later noted that while moving half-a-million people -- mostly Catholics -- might be acceptable for a totalitarian regime, human rights arguments would be an obstacle.

Other incentives, such as loyalty tests for benefits and large-scale internment "should drive out large numbers", they speculated.

The plans, which also discussed compensating unionists in areas ceded to the Republic, were quickly rejected as unrealistic and impractical.

But the fact they reached the desk of the British prime minister shows that they were considered at the top level.

The proposals are contained in UK government files from 1984, released today under the 30-year rule.

Officials revisited the border question in response to research by Paul Compton, an academic from Queen's University Belfast.

His "most respected analysis" is discussed in a secret paper prepared by the Northern Ireland Office. A copy sent to Mrs Thatcher and included in one of the files is heavily underlined, suggesting that she considered it in detail.

Dr Compton had described the partition of 1920 as "necessary and justified" but "flawed by the messy way in which it was executed".

He suggested three options for repartition, including one which would cede over half of the geographical area of Northern Ireland to the Republic, reducing its population to one million -- 73.5pc of which would be Protestant.

A more modest version, ceding parts of Fermanagh, south Armagh and most of Derry city, was also proposed.

The Catholic population would have been cut by 105,000 to around 460,000, while transferring only 30,000 Protestants to the Republic.

The briefing paper on Dr Compton's suggestions also referred to a possible partition of Belfast.

NIO officials discussed creating "a wedge-shaped area in west Belfast" running from Twinbrook to the Divis Flats, including areas such as Poleglass, Andersonstown and the Lower Falls.

The briefing paper discusses "difficulties over the Belfast sector", adding that one solution, "a walled ghetto", "would entail physical as well as political difficulties".

It adds: "Policing international boundaries across Belfast and any corridor between republican Belfast and the Border would be a formidable task."

Although the idea was quickly rejected, repartition re-emerged as a political issue in November 1984, when Taoiseach Garret FitzGerald spoke publicly against it.

Dr FitzGerald warned that it would lead to a more permanent division of the island.

On a minute referring to those remarks, Mrs Thatcher wrote: "That's why he doesn't like it."

Seperately, released papers show Taoiseach Garret FitzGerald was left depressed after the "profound personal and political setback" of an Anglo-Irish summit between himself and prime minister Margaret Thatcher, in which little progress was made in resolving problems in Northern Ireland.

UK state papers released by the National Archives in London from 1984 show that Dr FitzGerald wanted to advance co-operation between the two governments, whereas the British were considering whether or not to continue talks between the two countries at all.

Belfast Telegraph