Caltex said on Tuesday that Couche-Tard made an indicative A$34.50 a share offer, a nearly 16% premium to the petrol pump and convenience store operator's last closing price, and 7% higher than the A$32 per share offer it previously received from the Canadian company.

The previous offer had not been disclosed before Tuesday and Caltex called it "inadequate". It said discussions with Couche-Tard were at an early stage, and the proposal was conditional with no certainty that it would result in a deal.

Couche-Tard said it had initially approached Caltex on Oct. 11 when its offer was turned down, and came back with a revised proposal on Nov. 18.

Couche-Tard is willing to engage with Caltex to get a proposal to shareholders soon, its Chief Executive Brian Hannasch said in a statement.

If the deal goes ahead, it would mark Couche-Tard's first foray into Australia, and its largest deal, according to Refinitiv data. The Canadian company said it has been looking at Asia for several years.

Caltex is under pressure to turn around its business due to weak consumer demand and margin pressure from higher oil prices and has been reviewing its retail sites.

The new offer allows Caltex to pay a special dividend of up to A$8.41 a share but restricts it from selling assets, potentially hampering its plans for an initial public offering of up to 49% of its 250 convenience retail sites that it announced on Monday.

Hannasch said Couche-Tard was a "committed buyer of the entire Caltex business."

Caltex shares jumped 13.4% to close at their highest level in 15 months to A$33.79, but remained below the proposed price.

"The split of property assets from the operational aspects of the business was clearly aimed at the bidder and forced them to come back with a better offer," said Michael McCarthy, chief strategist at CMC Markets and Stockbroking.

Terry Couper, an analyst at Airlie Funds Management, Caltex's third-largest shareholder with a 4.8% stake, told Reuters the new offer undervalued Caltex's retail property and the "privileged position" of its fuel assets.

Couche-Tard said it holds about 2% of Caltex's shares.

UBS and Grant Samuel are advising Caltex on the proposal, while Goldman Sachs is advising Couche-Tard.

By Nikhil Nainan