Both firms want to know whether the ACCC has any concerns that would need to be overcome prior to their bid to acquire Dairy Farmers being formally assessed by the Co-operative's board.

The commencement of Fonterra's regulatory approval process this week follows that of Kirin-owned National Foods last month.

"As stated previously, Dairy Farmers’ Board has requested interested bidders seek the necessary regulatory clearances, including ACCC reviews, prior to it formally assessing proposals," Dairy Farmers chief executive Rob Gordon said earlier this week.

"Any bidder that does not have existing dairy operations in Australia would not, however, be expected to seek an ACCC review at this point.

"Such parties may be required to seek Foreign Investment Review Board (FIRB) approval during coming months.

"Dairy Farmers' board will meticulously assess each of the available options before it puts a recommendation to its dairy farmer shareholders."