Shares of Saskatoon-based Potash Corporation of Saskatchewan fell Tuesday, after the company said the extension of a takeover offer from BHP Billiton doesn't change its opposition to the bid.

PotashCorp again urged its shareholders to reject the "wholly inadequate" offer.

Saskatchewan Premier Brad Wall has publicly questioned whether a foreign takeover of PotashCorp would be good for his province or Canada. (CBC)

Its shares closed down $1.98 to $150.55 on the Toronto Stock Exchange.

BHP announced Monday it was extending the deadline for its offer of $130 US a share, or $38.6 billion, by one month to Nov. 18.

The move came the same day as the federal Competition Bureau requested more time to review the terms of the bid. Under the Competition Act, the deal can't go ahead for 30 days after BHP complies with the request.

BHP said in a release it plans to comply "expeditiously" with the Bureau's request.

The U.S. Securities and Exchange Commission is also examining the offer.

Also Monday, Saskatchewan Premier Brad Wall publicly questioned whether a foreign takeover of PotashCorp would be good for his province or Canada.

Wall made the comment after meeting with BHP CEO Marius Kloppers.

"The question needs to be, 'Are Saskatchewan people, are Canadians, better off as a result of this? Is our economy stronger as a result of this very large deal?'" Wall said.

"We're doing our homework, we'll see what all of that due diligence tells us, but as of today I'm having a hard time answering that question in the affirmative."

Kloppers said he would meet Canadian politicians this week as he sought to build support for his bid.

With files from The Associated Press