Caltex Australia has confirmed it has made a bid to buy Woolworths' fuel business, a move which would give it almost 40 per cent of the fuel retail market.
Caltex said its proposal is "confidential and conditional", but industry speculation has put a $1.5 billion price tag on the Woolworths business.
Woolworths' almost 600 outlets currently have about a 21 per cent share of the Australian fuel market, while Caltex - which is Australia's only publicly-listed refiner - holds about 16 per cent of the market.
Caltex has an exclusive contact with Woolworths petrol stations and currently supplies 3.5 billion litres a year to supermarket's convenience store chain.