Martin McGuinness (left) said Peter Robinson should give evidence at the Dublin hearing

The deputy first minister also attacked the length of time a criminal investigation is taking into the so-called Project Eagle controversy.

“There is a police investigation; they are investigating wrongdoing. Do I believe there was wrongdoing? Yes, I do,” he said.

Before a parliamentary committee in Dublin probing the £1.2 billion sale of Northern Ireland property loans by the Republic’s toxic assets agency Nama, Mr McGuinness accused former first minister Peter Robinson of excluding him from meetings leading up to the deal.

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The Sinn Fein chief also challenged the former DUP leader to appear before the hearings.

“I came here today as I have nothing to hide,” he told the Oireachtas Public Accounts Committee.

“I have done it, and I think anyone who is asked to come should come.”

Earlier this week, Mr Robinson told the Press Association he had not received an invite sent more than a month ago, adding that he was not answerable to Dublin but would like to be helpful.

The committee said it has couriered a fresh invite to his home, which has been acknowledged.

Mr McGuinness said his only involvement with the Project Eagle sale was in a conference call, along with Mr Robinson, in January 2014 during which Dublin’s Finance Minister Michael Noonan said the portfolio was going on the open market.

It was sold to American investment fund Cerberus in April that year.

Another US company, Pimco, has told the committee it pulled out of an earlier bid after it was asked for a “success fee” or fixer payment of £16 million for three parties behind the scenes.

The money was to be shared equally by Belfast businessman Frank Cushnahan, US law firm Brown Rudnick, and Ian Coulter, a managing partner of Tughans, a Belfast law firm subcontracted to assist in the deal, Pimco said.

Mr Cushnahan was formerly a Nama adviser on Northern Ireland, on the recommendation of the DUP .

Mr McGuinness said Mr Robinson told him about the Pimco withdrawal but did not explain their reasons for doing so. Neither did Nama or Mr Noonan inform him, he told the hearing.

Asked about Mr Robinson and Mr Cushnahan’s relationship, Mr McGuinness said: “I think they were very, very close.”

He added that any attempt by Nama to remove Mr Cushnahan from his advisory role “would have caused a major incident with the DUP”.

Brown Rudnick also acted as advisers in the successful deal with Cerberus, which has been dogged by scandal for more than a year, including £7 million linked to it being found in an Isle of Man bank account.

All parties have denied any wrongdoing.

Mr McGuinness said both Mr Robinson and then DUP Finance Minister Sammy Wilson “kept very closely to themselves” about their dealings with parties involved in the sale.

“It was quite clear the DUP was playing this very close to their chest,” he added.

Mr McGuinness said Mr Robinson and other members of the DUP had met with Pimco and Cerberus – including Cerberus chairman, the former US vice president Dan Quayle – without his knowledge.

Accusing Mr Robinson of “flying solo”, he said the former first minister also issued a statement after the sale from his own private office – not from the joint Office of First Minister and Deputy First Minister – welcoming the Cerberus deal.