Delta Electricity has not lodged an expression of interest for the Liddell coal-fired power station.
Deputy Prime Minister Barnaby Joyce told reporters in Canberra on Wednesday the company had "put an expression of interest out today ... in the purchase of Liddell".
But Delta company secretary Steve Gurney told AAP the firm had not lodged an expression of interest.
"Liddell is not for sale - it is not on the market," Mr Gurney said.
He referred AAP to a previous statement in which Delta said it would be prepared to undertake due diligence on Liddell, but had not been approached regarding the acquisition of the AGL-owned power station.
AGL chief Andy Vesey has told the federal government he will take to the board a proposal to keep Liddell open for another five years beyond its 2022 shutdown date, either by retaining ownership or selling it.
Alternatively, AGL would find other generation sources to cover the gap left by Liddell's closure.