Three-month stock chart for Athabaska Potash Inc. on the TSX. ((CBC))

BHP Billiton Canada Inc. has agreed to pay $341 million to acquire fertilizer company Athabasca Potash Inc. in a friendly deal between the two firms.

The offer values Saskatoon-based Athabasca Potash at $8.35 per share, roughly 25 per cent higher than the stock's closing price of $6.70 on the TSX on Wednesday.   

BHP's offer is also more than double what API's stock was last July 15 when Athabasca Potash said it was considering potential merger or takeover deals.   

As part of the deal, BHP Billiton Canada — a subsidiary of BHP Billiton of Australia, the world's biggest mining company — has the right to match any other offers for Athabasca Potash.

API has also agreed to pay a $12-million break fee to BHP Billiton if the deal ultimately falls apart under certain conditions.