Wesfarmers, one of the suitors for Coles Group, has remained tight-lipped on reports that it tried to raise its stake in the Australian retailer to fend off rival bids.

Wesfarmers, which already owns just under 13% of the voting rights in Coles, reportedly made the failed move to increase its stake late yesterday (1 May).

However, a Wesfarmers spokesman declined to comment on the reports. "We don't make any comments on speculation and it's speculation that (we tried to raise our stake)," the spokesman told just-food this morning. "We remain focused on trying to get access to the Coles' data room, which we still haven't succeeded in doing."

The spokesman said Wesfarmers and Coles are haggling over the rules surrounding due diligence on the retailer. "I simply cannot say when due diligence will begin," he said.

Wesfarmers has offered A$19.7bn ($16.4bn) for Coles in a consortium with Australia's Macquarie Bank and private equity firms Pacific Equity Partners and Permira.

A second consortium, led by private equity group KKR, has also lodged a bid and plans to at least match the Wesfarmers offer.

Woolworths, Australia's largest retailer, has also signalled its interest in taking on some of Coles' businesses. Meanwhile, Tesco, the UK's largest retailer, has remained coy on its reported interest in joining the Coles auction.

Coles decided to pursue a possible sale after a failed restructuring, while it warned in February that its profits for fiscal 2008 were likely to fall by 10%.