WINNIPEG, Manitoba, March 4 (Reuters) - BHP has signed non-binding sales agreements for all potash production from both phases of the Canadian mine it is building, and will look to convert those into firm offtakes within 12-18 months, a senior executive told Reuters.

BHP Chief Commercial Officer Ragnar Udd also said the company is not interested in acquiring the idled Cobre Panama copper mine from First Quantum Minerals.

Australia-based BHP's entry into selling potash is expected to shake up the global fertilizer market, which is dominated by producers in Canada, Belarus and Russia. Fertilizer is a key input for farmers to boost yields of crops such as corn.

BHP expects to begin production at its Jansen, Saskatchewan mine in late 2026, ramping up to 4.35 million metric tons annually. A second phase approved by BHP will boost yearly output to 8.5 million tons.

BHP plans to sell potash to distributors, rather than directly to companies that re-sell the fertilizer to farmers, Udd said.

"Our opening (sales) approach doesn't take us as far down the supply chain as potentially others do, which actually allows BHP to specialize in where we actually excel, in the rock production of resources," Udd said in an interview.

BHP has not previously disclosed the sales agreements or how it will market its potash.

BHP, best-known for mining iron ore, copper, nickel and metallurgical coal, is not interested in acquiring First Quantum's Cobre Panama, one of the world's largest open-pit copper mines, which was forced to shut down in December after Panama's top court ruled that its contract was unconstitutional.

"Honestly, while we're always looking for opportunities, I think that's a situation best left for Panama and others," Udd said. (Reporting by Rod Nickel in Winnipeg; additional reporting by Divya Rajagopal in Toronto, Editing by Franklin Paul)