(CNN) — An Irish man who has been in US immigration detention for five months has said he fears for his life and is confined in appalling conditions, as international scrutiny grows over the treatment of immigrants held by US authorities.

Seamus Culleton, originally from the Irish county of Kilkenny, has been held at an Immigration and Customs Enforcement (ICE) detention facility in Texas since early September.

Culleton, who has lived in Boston for more than 15 years and runs a construction company, told Irish broadcaster RTE that he was taken by ICE officers on his way home from Home Depot.

Culleton said that he told ICE authorities that he is married to a US citizen, is in the process of applying for a green card, had no criminal record and had a valid work permit.

“As far as I know I was covered,” he said, speaking from an ICE facility in El Paso, Texas where he is currently detained. “None of that mattered; they cuffed me and took me away,” he said.

In a statement to CNN, US Department of Homeland Security (DHS) spokesperson Tricia McLaughlin said that Culleton had entered the US in 2009 under the visa waiver program which allowed a 90-day stay, then failed to depart.

Culleton said that he is being held in a large, overcrowded room with more than 70 other men and sleeping under constant artificial lighting in cold and damp conditions.

Detainees are receiving limited food, have restricted access to medical care and are rarely allowed outside, he told RTE.

“I’ve been locked in the same room now for four and a half months. I’ve had barely any outside time. No fresh air. No sunshine. I could probably count on both hands the amount of times I’ve been outside,” Culleton said, adding: “I’m just locked in this room all day every day.”

Culleton described the conditions inside the facility, thousands of miles away from his home in Boston, as “filthy,” calling it a “nightmare.”“I’m in fear for my life down here, honestly,” he said.