EG Group, one of the world’s largest independent gas station and convenience store chains, is considering a bid for Caltex Australia Ltd. in a move that could start a takeover battle with Alimentation Couche-Tard Inc., people familiar with the matter said.

U.K.-based EG Group is working with a financial adviser as it evaluates making an offer for Caltex, which has a market value of A$8.6 billion (US$5.9 billion), the people said. No final decisions have been made, and there’s no certainty that closely-held EG Group will proceed with a firm bid, the people said, asking not to be identified as the matter is private.

Acquiring Caltex would bring a network of about 2,000 sites across Australia. Caltex last month rejected Couche-Tard’s latest offer of A$8.6 billion as too low, saying it undervalued the Sydney-based company.

The Canadian convenience-store giant, which owns the Circle K chain, had already raised the bid to A$34.50 per share in cash from its original proposal of A$32. Still, Caltex left the door open to a deal, saying it would give Couche-Tard access to select non-public information to allow it to improve its offer.

A representative for EG Group declined to comment, while Caltex didn’t immediately respond to an email seeking comment outside regular business hours.

EG Group has been making a series of acquisitions to expand its reach globally over the past few years. The company, whose investors include buyout firm TDR Capital, last year completed the A$1.73 billion purchase of 540 Australian fuel convenience sites from Woolworths Group Ltd.

It agreed in July to buy Cumberland Farms, gaining 600 locations in a deal that made it the fifth-largest independent convenience store operator in the United States. In 2018, EG Group spent US$2.15 billion to acquire Kroger Co.’s U.S. convenience store business.

EG Group is considering an IPO that could value it at more than 10 billion pounds (US$13.1 billion), people with knowledge of the matter said in October. The company was formed in 2016 when Euro Garages, run by billionaire brothers Mohsin and Zuber Issa, merged with TDR’s European Forecourt Retail Group.

It now has about 5,000 fuel station and convenience store sites across Europe, North America and Australia, according to EG Group’s website.