The Colombian army said today it has arrested a fourth man suspected of being a member of the IRA, less than two weeks after the arrests of three other Irishmen with alleged links to the paramilitary group.
The man, whose identity is unknown, was arrested today in Colombia's southern Huila Province, a military source told reporters.
"We have arrested an Irishman. We are investigating if he is a member of the IRA", the source said, without providing more information.
A British Embassy official in Bogota told reports he was unaware of the arrest.
The Colombian army on August 11th arrested three men which it alleges links were training leftist FARC guerrillas in making bombs and non-conventional weapons.
The men, identified as Mr Niall Terence Connolly, Mr Martin McCauley and Mr James Monaghan, are being held in a maximum security prison in Bogota and Colombia's public prosecutor's office has eight months to prepare a case
The three men told prosecutors they were visiting Colombia to see the Amazon, write about wildlife and learn Spanish, court documents show.
According to sources they said they never met FARC rebels and that all they knew about Colombia's 37-year-old war and rebel activity came from newspapers.
Meanwhile Sinn Féin party president Mr Gerry Adams faced further calls today to issue a public statement on the state of the IRA ceasefire.
Ulster Unionist minister on the Stormont Executive Mr Michael McGimpsey berated the West Belfast MP for not yet issuing a public statement on the recent arrest of three IRA suspects in Colombia.
Mr McGimpsey claimed the silence of Mr Adams in the light of the arrests in Colombia had been "deafening".
"The damning evidence that has been emerging from Colombia on a day and daily basis categorically points to the fact that republicans are heavily engaged with the armed Marxist grouping known as FARC," the South Belfast MLA said.
"Mr Adams's refusal to come clean demonstrates his contempt for society and illustrates the bad faith of the Republican Movement.
In a television interview last night, Minister for Foreign Affairs, Mr Brian Cowen, said the arrests raised "very serious concerns - and credibility questions".
The minister said: "What have been emerging are a lot of conflicting stories, and I do not want to add to that.
"But clearly the credibility questions that are arising need to be addressed. And I think the best way of addressing them is by re-establishing contact with the De Chastelain commission and building on the progress that has been made."
Mr Cowen said it would be "very odd indeed" not to be disappointed and concerned at arrests of the nature of those in Colombia.
It also emerged last night a right-wing paramilitary group in the country claimed one of the suspects also offered to work for them.
A letter signed by Mr Carlos Castano, of the right-wing United Self-Defence Forces of Colombia, or AUC, appeared on the group's web site today claiming one of the three men had approached his organisation offering "his professional services".