Tánaiste Joan Burton has called for an independent inquiry by a "competent authority" into the controversial sale of construction services company Siteserv.

Ms Burton also said she favoured a review of any transactions of equal magnitude worthy of inquiry by the Irish Banking Resolution Corporation.

She had heard the suggestions about the C&AG and said, “I’m aware...that there may have to be some change of legislation if that were to be facilitated.

“But certainly the C&AG has played a very valuable role in scoping inquiries and investigation. It’s a matter for identifying what is the best mechanism for a competent inquiry.”

The Taoiseach said on Wednesday that the C&AG would carry out the investigation.

Fianna Fail leader Micheál Martin said people did not want a scoping inquiry and there should be Commission of Investigation.

Ms Burton told him there were a number of possibilities including the Comptroller & Auditor General or a Commission of Investigation.

But she said the Government had made no decision yet.

For the third day leaders’ questions was dominated by the controversy surrounding Siteserv, which was sold for €45 million by IBRC to businessman Denis O’Brien’s Millington at a cost to the State of €105 million.

Mr Martin said the proper authority was the Commission of Investigation.

It could look at Siteserv and other transactions, he said.

He cited two other companies which had offered more for the firm and pointed out that €5 million of the €45 million sale went to the company’s shareholders.

Ms Burton told him there were more than shareholders involved in the company. There were 1,500 people employed and now the firm had more than 3,000 workers following the sale, she said.

Sinn Féin deputy leader Mary Lou McDonald accused the Tánaiste of kicking for touch. Ms McDonald said the C&AG had clearly stated that he had no remit to deal with IBRC.

She referred to other high value transactions.

She called on Ms Burton to commit to a Commission of Inquiry and claimed the Government repeatedly hid behind commercial sensitivities.

She claimed civil servants’ concerns were ignored and that instead Minister for Finance Michael Noonan took the word of IBRC chairman Alan Dukes, a former leader of Fine Gael.

Socialist Party TD Ruth Coppinger said she thought Fine Gael would have steered clear of Mr O'Brien, whom she said had links with Fine Gael and who had been the subject of a tribunal of inquiry where adverse findings were made. She also named a number of Siteserv directors.

Ms Coppinger was told she should not name people not there to defend themselves. The Tánaiste accused her of taking “cheap shots”.

Ms Coppinger accused Ms Burton of “swaggering” and said people looking at their water charges’ bills were totally justified in refusing to pay when they saw and see how others were making millions.

Ms Burton told her that a million people had registered with Irish Water and people wanted a good water supply, which was also needed for the economy.