Independent TD Catherine Murphy says Denis O'Brien was approached by personnel in IBRC telling him to increase his bid, in order to secure the sale.
She's again told the Dáil that other companies had come forward making higher bids for SiteServ – but Mr O'Brien's firm still emerged as the preferred bidder.
Deputy Murphy made her comments under Dáil privilege during a debate on the IBRC Commission of Investigation.
Meanwhile the Minister for Finance, Michael Noonan, has said concerns raised by Sinn Féín's Pearse Doherty last night will be covered by the inquiry.
Deputy Doherty says IBRC's liquidators rejected three bids by Denis O'Brien to renegotiate loans worth €315 million – but then agreed to a fourth proposal after Mr O'Brien threatened legal action.
Pearse Doherty says the terms of reference won't allow the claims to be investigated, but Minister Noonan last night said they would be.
For their part, the special liquidators for IBRC have disputed Pearse Doherty's claims.
They say the information put on the Dail record about the alleged extension of credit facilities was inaccurate and misleading.
