TD Paul Murphy has said there 'absolutely' has to be an investigation into Robert Troy by the Standards In Public Office Commission (SIPO).
It comes after the Minister of State apologised "unreservedly" for serious mistakes in his register of interests.
The Fianna Fáil TD made seven amendments to his declaration, dating back to 2011.
Deputy Murphy told Newstalk Breakfast Mr Troy's apology brought more issues to light.
"He apologised unreservedly after he got caught, not before he got caught, after a whole series of articles came out on The Ditch and other news sites.
"Even in his statement yesterday - where he apologises unreservedly - he admits to a whole series of new, previously undisclosed breaches of the ethics legislation.
"Effectively, TDs are required to declare interests in what's known as the Register of Members Interests when they're elected, and then every single year.
"By my count he has admitted to at least nine breaches now.
"That's four breaches of not declaring property over a certain value that he owned, three breaches of not declaring directorship of a company, and then another two breaches of not declaring contracts that he had.
"It seems to be ongoing that he has two lease agreements of properties he owns - he effectively leases to the council under a RAS scheme.
"And then there's a kind of dispute whether over another two, which would bring us to 11, would or would not count as breaches: which is two sales of property that he made to two different councils.
"So he's just wildly, flagrantly in breach of the ethics legislation.
"In these circumstances, there absolutely has to be an investigation".
He says the whole point of the legislation is transparency.
"We have this law in place in order that this should be public knowledge.
"This stuff has to be on the public record.
"The fact that he has two lease agreements, which he has never declared - he only references it in his apology - with Westmeath County Council is quite significant.
"He has contracts with a public body for property that he owns: not declaring it, that's precisely what this legislation is for".
