The three captured men were shown to the media
The BBC's Claire Marshall in Bogota says the anti-terrorism investigating judge could take 18 months to bring formal charges against the men.
The three, named as Martin McCauley, James Monaghan and David Bracken, were arrested at Bogota airport on Saturday after arriving on a flight from an area in southern Colombia under the control of rebels of the Revolutionary Armed Forces of Colombia (FARC).
Two of the men have served prison sentences for bomb-making in the United Kingdom.
Analysts say the acquisition by the FARC of new bomb-making skills could mark a significant development in Colombia's decades-old civil war.
The IRA suspects had spent at least five weeks in territory held by the rebels before their arrest.
False passports
The three were presented to the media at a press conference in the capital, Bogota, where they are still being questioned.
Police named two as James Monaghan and Martin McCauley, both of whom were previously convicted in the UK on bomb-making charges and membership of the Provisional IRA.
The third man, the only Spanish-speaker and apparently the leader of the group, has not been formally identified, though he was travelling under the name of David Bracken.
They were all holding fake British or Irish passports.
The Colombian security forces had been unable to arrest the men for five weeks because they were in a safe haven set up after negotiations between the government and the FARC.
They were picked up when they arrived off an internal flight from the FARC territory to make a connection to Paris.
It is understood that forensic examination of the men's clothing and luggage has shown traces of explosives and the three could face charges of entering the country with false papers and "training an illegal army in terrorism".
Fears
Colombian armed forces chief General Fernando Tapias said the military had noted growing coincidences between tactics used by Colombian rebels and the IRA.
He gave as an example the FARC's growing use of devastating homemade missiles to attack villages.
The BBC correspondent in Bogota says the Colombian security forces are extremely worried at the presence of the IRA bomb experts.
Mr Monaghan is a known explosives expert, and Mr McCauly specializes in home-made weapons and mortars.
The knowledge they have in their heads could change the nature of Colombia's 37-year civil conflict.
The FARC recently threatened to bring their war, until now confined mainly to the countryside, into the cities.
Our correspondent says that if the FARC now develops skills in urban guerrilla warfare, the Colombian security forces could find themselves out of their depth.
The Farc's attractions for the IRA would seem to be either a slice of its vast arsenal, which is believed to include surface-to-air missiles, or simply some of the money it is believed to make from hostage-taking and drug-running.