The multi-million-dollar deal to sell designated Brisbane parkland to a Liberal National Party donor has been referred to the Crime and Corruption Commission (CCC).

Key points: The Lord Mayor says he was aware prospective buyer Boon Tan was an LNP donor

The Lord Mayor says he was aware prospective buyer Boon Tan was an LNP donor Dr Tan and companies connected to him contributed about $50,000 to the LNP last financial year, according to AEC

Dr Tan and companies connected to him contributed about $50,000 to the LNP last financial year, according to AEC Labor's Rod Harding said the BCC had failed the transparency test

On Tuesday, the ABC revealed the Brisbane City Council (BCC) signed a $3.3 million conditional contract to sell the land near Brisbane Airport, without public tender or auction.

The CCC confirmed the case had been referred.

"The CCC will assess this matter in accordance with its standard processes," it said in a statement.

"It is not appropriate for the CCC to comment further while the assessment process remains ongoing."

Lord Mayor Graham Quirk told the ABC he was aware the prospective buyer, Boon Tan, was an LNP donor.

"Mr Tan approached me in the middle of last year about his [car rental] business, it was booming, it was busting at the seams, he was seeking additional land," Cr Quirk said.

The Lord Mayor said the deal was in the public interest because Dr Tan was prepared to pay $400,000 above the market value for the 8,521-square-metre block.

But for the sale to go ahead, the BCC had to seek a ministerial exemption, which it applied for last year.

In its application for an exemption from the public tender process, the Council declared "no material personal interests on the part of any councillor of Council exists in relation to the proposed disposal of the property".

Donation declarations on the Electoral Commission website reveal Dr Tan and companies connected to him contributed about $50,000 to the LNP last financial year.

Dr Tan has told the ABC his offer for the land "was made through proper channels, is not unusual and is subject to a range of normal conditions".

He said the offer was made with the utmost propriety.

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Labor's lord mayoral candidate, Rod Harding, said the BCC had failed the transparency test.

"They actually signed the forms saying there was no potential conflict of interest, even though the buyer was a long-term donor to the LNP," Mr Harding said.

The $3.3 million deal was vetoed late last week after Local Government Minister and Deputy Premier Jackie Trad rejected the application.

Her department told the ABC the "BCC failed to provide sufficient evidence to support an exemption from an open tender or auction for the sale of this land".

The ABC asked the Department of Infrastructure, Local Government and Planning if it had referred the matter to the CCC for investigation.

It responded by saying "the Department does not provide comment on individual allegations and matters that may be under consideration or referred to another body."