The suggestion that the three Republicans were vacationing in Colombia rather than training rebels was said to be an “insult to the intelligence community” by diplomats, according to archival documents.
At the time, there were concerns that the arrests of the so-called Columbia Three in 2001 could damage the peace process in Northern Ireland.
The incident occurred after the IRA agreed on how to disable the arsenal after months of slow progress.
Colombian authorities claimed the men were training members of Colombia’s Revolutionary Armed Forces, also known as the Farc.
The men were convicted in 2004 of training rebels and sentenced to 17 years in prison. They were granted amnesty in 2020 as part of Colombia’s peace process.
In 2022, it was reported that their pardons were revoked.
The Colombian Three have always denied any wrongdoing and maintain that they were in the country to observe peace negotiations in Colombia.
Three men, Niall Connolly, James Monaghan and Martin McCauley, who were traveling on fake passports, were arrested at Bogotá International Airport on August 11, 2001.
Newly released state documents show that talks between senior Irish and American officials after the arrests showed Richard Haass, the US special envoy for Northern Ireland, was furious about the incident.
During a meeting between Mr Haas and the Irish Ambassador to the US, Seán O’Whiggin, Mr Haas said the men were “not on holiday and they are not promoting the peace process”.
“Attempting to provide such an explanation was not only implausible, it was an insult to our intelligence.
“It would be much better to admit that a mistake was made and say it will never happen again.
“It is much more likely that the detainees were involved in some kind of ‘transfer of bomb-making know-how.’
The briefing document, written for the Foreign Office, details a meeting between Mr Haas and the Irish Ambassador to the US, Seán O’Whiggin, in Washington, DC.
The document notes that the Irish and British governments were “clearly in inventory mode to develop strategies related to the progress of the peace process, including on the Colombian issue”.
“The reasonable explanation that the three may have been engaged in peace education is not sustainable.
“Rather, the choice was from a more sinister menu, such as handling certain types of weapons, experimentation, and training,” the memo, dated September 7, 2001, said.
This material can be viewed in the National Archives, file 2023/53/29.