Couche-Tard is "in the middle of our due diligence process, and we'll get comfortable by applying our usual rigor and discipline around M&A," Hannasch told analysts on an earnings call early on Thursday, Australian time.

Caltex's shares have plunged about 40% since Couche-Tard raised its offer to A$8.8 billion in mid-February and privately owned UK convenience store retailer EG Group made a rival offer of A$3.9 billion in cash for its convenience stores plus shares in a spin-off company with its refining and fuel distribution assets.

As a big supplier of jet fuel in Australia, Caltex has been hit particularly hard by airlines grounding their fleets.

Caltex's shares hit a more than six-year low on Thursday then rose 3.1% to 20.39 after Hannasch's comments, but remain well below Couche-Tard's offer price of A$35.25 a share.

Hannasch said he expected the global landscape for credit and acquisition multiples would change dramatically.

"And our goal is to be ready if the right opportunities present themselves," he told analysts.

Hannasch said Couche-Tard remains committed to acquiring all of Caltex's assets.

"And then I would say due diligence has also reinforced the fact that Caltex has a very strong team with a high level of expertise around the full value chain," he added.

Caltex declined to comment on Thursday on whether it was still talking to EG Group, beyond citing its previous statements to the market. EG Group also declined to comment.

Caltex in February rejected EG Group's offer, but said it was open to talks with the company about a potential transaction.

(Reporting by Sonali Paul; Editing by Amy Caren Daniel)