An Irish finalist for the audacious Mars One project to start a human colony on the red planet predicted the plan would fall "on its face" on Tuesday.

Joseph Roche, an astrophysicist at Trinity College Dublin, said the selection process for the one-way trip was deeply inadequate, and that finalists were encouraged to give money to the project.

"My nightmare about it is that people continue to support it and give it money and attention, and it then gets to the point where it inevitably falls on its face," Roche told Medium magazine.

"If I was somehow linked to something that could do damage to the public perception of science, that is my nightmare scenario."

Mars One, a Dutch-based non-profit, has been repeatedly criticised over its plan to colonise Mars from 2024.

Dutch Nobel Physics prize winner Gerard 't Hooft, an early backer of the project, has said that it will far cost more and take longer than planned.

A study by Massachusetts Institute of Technology researchers found that humans would start dying within 68 days on the colony, and a TV deal intended to help fund the project reportedly fell through.

Roche, an assistant professor, said that candidates for the trip were awarded "points" in return for buying Mars One merchandise or donating to the project.

Initial plans for an interview process lasting several days never materialised after candidates signed a non-disclosure agreement, he said.

"I have not met anyone from Mars One in person," Roche said.

"All the info they have collected on me is a crap video I made, an application form that I filled out with mostly one-word answers... and then a 10-minute Skype interview."

"That is just not enough info to make a Judgment on someone about anything."

The group did not respond to AFP's request for comment on Roche's claims, but told New Scientist magazine that donations from candidates did not influence the selection process, and that a new TV deal was in place.

Roche did not indicate whether or not he planned to drop out of the project.