Fonterra has been forced to disclose details of a joint-venture deal with French company Sodima/Yoplait by Australia's Takeover Panel.
Filipino company San Miguel went to the panel last month alleging unacceptable circumstances in Fonterra's takeover bid for National Foods.
San Miguel, which is a rival bidder for National Foods, claimedthere had been inadequate disclosure about the possible joint venture.
The panel did not make a declaration of unacceptable circumstances, but said it had accepted undertakings from Fonterra to disclose the full extent of the joint venture.
The panel agreed with San Miguel by recognising Fonterra and Sodima were joint partners in the attempted takeover of National Foods.
A San Miguel spokesman described the ruling as a "huge win".
Fonterra had a binding 50-50 joint venture with Sodima that would procure National Foods' high margin supermarket products in a successful takeover.
National Foods distributes the Yoplait brand in Australia and New Zealand.
An industry source said the venture would equate to about 35 per cent of National Foods' value, or about A$646 million ($710.82 million), with half of that going to Sodima.
"It doesn't look like Yoplait (Sodima) is throwing in any assets at all," the source said.
Fonterra has already provided the panel with a draft supplementary bidder's statement which includes details on the joint venture, which the panel has forwarded to National Foods and San Miguel to give them a chance to make submissions regarding its contents.
Fonterra has agreed to lodge the supplementary bidder's statement with the Australian Stock Exchange and the Australian Securities and Investments Commission as well as send it out to National Foods' shareholders within 14 days.
The panel also ruled that Fonterra offer withdrawal rights to National Foods shareholders who had accepted Fonterra's bid.
