By Agence France-Presse
APA's assets include gas transmission pipelines and storage, along with wind and solar farms across Australia. The firm's website said its 15,000 kilometres (9,300 miles) of gas pipelines connect 1.3 million Australian homes and business.
The Aus$11 per share cash offer was a 33 percent premium to the company's Aus$8.27 closing price on Tuesday, with the stock soaring 20.92 percent to finish at Aus$10.00 on Wednesday.
Chairman Michael Fraser said it was in shareholders' interests to engage further and agreed to allow the Hong Kong powerhouse to undertake due diligence.
"The APA board will continue to evaluate the proposal and will update APA's security holders and the market as appropriate," Fraser said in a statement.
All up, APA owns and/or manages and operates a portfolio of assets worth in excess Aus$20 billion.
CK Infrastructure chairman Edmond Ip said the proposal was "still at a preliminary stage and ... the transaction may or may not be undertaken".
Any takeover would be subject to Foreign Investment Review Board approval, with the consortium, comprising CK Infrastructure Holdings, CK Asset Holdings and Power Assets Holdings, saying it had already held preliminary talks with the FIRB.
CK Infrastructure already owns Australian interests including power provider Duet Group and the deal would involve some of APA's assets being divested to secure clearance from the country's competition watchdog.
They would include APA's stake in the Goldfields and Parmelia gas pipelines in Western Australia and in the Mondarra gas storage plant in the same state.
The move on APA is the latest in a string of takeovers in recent years by CK Infrastructure in Australia, including Duet Group last year and gas distributor Envestra in 2014.