Taoiseach Enda Kenny was criticised yesterday over his attitude to the £1.3bn Nama northern property deal.
Fianna Fail leader Micheal Martin said questions remain over the sale of Northern Ireland assets owned by the Dublin government's "bad bank" to US investment firm Cerberus last year.
He has called for a state inquiry into the affair.
"It's quite a dramatic contrast, in terms of the respective responses from the two jurisdictions," he told Mr Kenny, during questions in the Dail.
"It's about ethics. Was the deal done ethically? Nama seems to be saying everything is okay on the seller side, we are not really responsible or that bothered about what happens on the purchaser side, that satisfies us, we got the best value for money - or so we think."
The UK's National Crime Agency (NCA) is leading an investigation into the sale after allegations levelled in the Dail by Independent TD Mick Wallace.
Mr Martin said finance minister Michael Noonan knew as far back as March last year that former Nama adviser Frank Cushnahan was to be paid £5m by another US investment fund, Pimco, if it won the bidding war for the portfolio. Pimco said it later withdrew.
"It's shocking and no one batted an eyelid," Mr Martin said.
He added that allowing the sale to go ahead to Cerberus was at the least an extraordinary error of judgment.
Mr Kenny said there have been no allegations of wrongdoing against Nama and the portfolio was eventually sold in an open process to the highest bidder.
"The only potentially illegal activity we are aware of here to date is the potential diversion of funds due to a Northern Ireland law firm, and allegations raised are being taken very seriously by authorities," he said.
Sinn Fein deputy leader Mary Lou McDonald also called for an inquiry.
