While a report says the provincial treasury stands to lose $200 million a year if BHP Billiton takes over Potash Corporation of Saskatchewan, the revenue loss would be even worse than that, PotashCorp says.

On Monday, the Conference Board of Canada released a report on the impact of a PotashCorp sale that was commissioned by the provincial government.

Saskatchewan, which has more than 30 per cent of the world's potash, typically receives several hundred millions of dollars annually in taxes and royalties connected to the pink mineral.

However, if Billiton's $38.5-billion US bid to buy PotashCorp succeeds, the company would be able to avail itself of tax writeoffs and Saskatchewan would lose out on some $2 billion over a decade, the report said.

In a filing late Monday with the U.S. Securities and Exchange Commission, PotashCorp responded, saying that projected revenue loss was "understated." The Saskatoon-based company didn't say how much more it would really be.

The Conference Board report said that a new buyer might adopt a high-production, low-price strategy that would cause an even bigger hit to the provincial treasury — $5.7 billion over 10 years.

The Conference Board said it was unlikely that Billiton would adopt that strategy, but in its SEC filing, PotashCorp appears to disagree.

"The report chose to assume that BHP would not operate full out in direct contradiction of previous BHP statements," the company said.

PotashCorp also said it relayed its position to the Conference Board, but was ignored.