Finian McGrath (Independent, Dublin North Central) said he had been approached by a group of workers alleging serious ill-treatment.
He said there were "allegations of exploitation, intimidation, breaches of employee rights, dismissals, failure to pay staff, mandatory working, the use of sleepers, threats and allegations of sexual harassment".
Mr McGrath, who was advised by Ceann Comhairle Rory O'Hanlon that he could not name the company under the rules of the House, said he had no alternative but to speak out and demand the truth.
"This is Ireland 2005, not Dublin 1913," Mr McGrath said.
He said he had met other members of the company in question recently. "They denied all the allegations, except the non-payment of staff issue. It is important we get to the bottom of these allegations".
