A secretary at the New York Bureau office of the FBI was suspected of being a mole, passing classified information on to IRA members plotting to assassinate Margaret Thatcher, newly released documents to the Guardian newspaper reveal.

FBI agents also noted that two of the alleged killers of Captain Robert Nairac, a British undercover agent who “ran” several loyalist killers, were living in the US.

Nairac was kidnapped outside a pub in South Armagh and murdered by the IRA. His body has never been found.

There was one serious attempt to assassinate Thatcher it seems. In 1992, an FBI informer in the Irish Republican community in the Boston area informed federal agents that two men in New York involved with the Provisional IRA (PIRA) were planning to assassinate the by then former Prime Minister during one of her speaking engagements in the US in September of the same year.

The names of both of the men have been redacted, along with other identifying details, but the documents do note they were believed to be “capable of carrying out such an attack based on their backgrounds and professional expertise.” At least one of the men was suspected to have been behind a previous bomb attack in the UK, and one was married to a US citizen and had been a resident alien since 1965.

The source had heard about the plot at an unnamed bar in New York thought to be a “hotbed” of IRA activity and owned by an IRA member.

At one point in the documents, the suspects are referred to as “Provisional Sinn Fein leaders.”

The same internal FBI communication points to the potential mole at the FBI’s New York bureau, noting, “In addition to the information concerning the Thatcher threat, the source advised that there was a leak in the New York FBI office coming from a secretary that gave PIRA access to name checks,” and further cautions that “independent allegations of a leak in the Neu [sic] York office have previously surfaced.”

There were reportedly multiple plans to murder the British Prime Minister during her visits to the US throughout the 1980s and 90s. Details of these and other FBI investigations into the assassination plots are contained in hundreds of pages of documents released to The Guardian newspaper on Monday.

They were made public following a freedom of information request issued after Thatcher’s death at 87 years of age on April 8, 2013.

It seems that initially the FBI caught wind of a plot almost by accident – an FBI source was in the cocktail lounge at the Boar’s Head, a restaurant in Falls Church, Virginia, in February 1981 when he overheard two men with “English or Irish accents” talking about a possible “hit” during Margaret Thatcher’s upcoming visits to New York and Washington DC.

One man said that the plan would “even the score for H,” likely in reference to Cell Block H at the Maze Prison in Northern Ireland where IRA prisoners were held. His friend tried to “quiet him down.”

The FBI followed up the dubious information, but ended up seeking a polygraph for the alleged informant which he refused. Later surveillance revealed “three known IRA terrorists” living in the Falls Church area. Their names are redacted from the newly released files. Thatcher’s 1981 visit came and went without any attempts on her life and the case was declared closed in March.

The documents reveal the details of other such cases, including a 1987 confession by an Englishman, who had been arrested for stealing a motorcycle, that he had been traveling to Camp David, where Thatcher was visiting Ronald Reagan, to kill the Prime Minister. With a previous criminal record for assault, he was no longer allowed to return to England and had become enraged over that fact. The file also mentions that the man had dreamt that Thatcher was his mother.

As for the 1992 plot, The Guardian notes that Thatcher’s visit passed without incident and that the Iron Lady was “able to complete her 12-day itinerary, which as well as a visit to Bush in the White House and lunches with high-powered American officials included six separate hair appointments.”

Former Prime Minister Margaret Thatcher.Wikicommons