Metcash Trading chief executive Andrew Reitzer said no decisions would be made until Coles Myer has finalised its deal with Shell, due in about two weeks.

"If Coles ties up Shell, the other two or three petrol companies are left without a retail partner, at that stage, we're effectively the only other force in the retail market that could deliver," Mr Reitzer told the Australian Financial Review.

Reitzer said unlike Coles, which is to spend $200 million acquiring Shell's premium sites, Metcash and its 1100 IGA members would not acquire petrol outlets but would offer a loyalty-style discount program.