Shell spokesperson Helen Morgner said the company is constantly involved in negotiating with third parties in regard to expanding business opportunities. However, "This (buyout rumours) is nothing new. Speculation has been around for quite a while and we don't comment on speculation," Ms Morgner said.

A report in Australian Financial Review said Coles-Myer is making the move to combat the success of arch-rival Woolworths, which now owns 280 outlets and is selling 45 million litres of petrol a year, or about 10% of the national market.

A successful deal with Shell would catapult Coles to petrol leadership in Australia with about 27% of the market, the AFR said.