Murray Goulburn chief Gary Helou has attacked the Abbott government, claiming it hasn't given the co-operative a "level playing field" in its fight to take over Warrnambool Cheese & Butter.
Warrnambool is at the centre of a three-way global tussle, with Canadian dairy giant Saputo the leading bidder, ahead of MG and NSW-based Bega Cheese.
Mr Helou, the managing director of Australia's biggest dairy company, told MG shareholders in Melbourne on Friday that he felt the government had "handicapped" the co-operative's bid, which hinges on approval from the competition regulator.
His comments came as MG proposed a partial float of the farmer-controlled co-operative along similar lines to Fonterra's set-up of a non-voting shareholders' fund.
Mr Helou said he was "bitterly disappointed" that Treasurer Joe Hockey gave Saputo foreign investment approval before MG had its chance to put its case before the Australian Competition Tribunal - a process which could take six months.
Saputo can start paying WCB shareholders its offer of $9 cash a share, or $505 million, next month, having declared its bid unconditional.
"We are disappointed the Foreign Investment Review Board rushed through this," Mr Helou said.
"Maybe it isn't in the national interest [for Saputo to buy WCB] but it's in the national interest to wait and hear our case.
"To have an unlevel playing field in our own home country ... it's a bit hard to swallow."
Murray Goulburn, which owns about 17 per cent of WCB, has also offered $9 cash a share, lobbing its revised bid last Wednesday. Two days later Saputo matched the bid and trumped MG by declaring it unconditional.
MG chairman Phil Tracy said he felt as though the co-operative had "one hand tied behind its back" in the bidding process.
Mr Helou gave shareholders no indication whether MG would raise its bid, saying merely that the board had the right to review its offer.
United Dairy Farmers of Victoria sent a senior delegation to Canberra on Thursday to lobby the government to keep WCB in Australian hands.
UDV president Kerry Callow and vice-president Tyran Jones argued that local suitors Bega and Murray Goulburn had been unfairly treated.
But David Lord, the chief executive of WCB, which has unanimously backed Saputo's offer, dismissed those claims.
"The playing field is completely level," Mr Lord said. "All the parties know what are the requirements and what are the clearances they need. They all understand the rules.
"Some of them have been much faster to move on these clearances than others."
Mr Lord said Murray Goulburn had been playing "catch-up" with Saputo and Bega, which has declared its offer of $2 cash and 1.5 Bega shares unconditional.
MG is yet to make its submission to the Australian Competition Tribunal, which Mr Helou said would be lodged on November 29.
Mr Lord said this presents a significant risk to WCB shareholders because other bidders could walk away in the time the tribunal takes to make its decision. Alternatively the tribunal could dismiss MG's application, he said.
MG intends to present the full structure of its partial float at its 2014 annual meeting. Mr Helou said that amount of time was needed to consult with MG's shareholders.
He said the proposal would not change MG's co-operative structure or lessen farmer control.