TORONTO, Sept 8 (Reuters) - The union representing workers at the Panama copper mine of First Quantum Minerals (FM.TO) threatened to go on strike from Saturday over a wage negotiation impasse with company management, according to a statement published on the union's Instagram page.

Union members of the Canadian miner's Panama operations said the negotiation remained stuck on disagreements over profit sharing and salary increase.

"The company proposes an incentive instead of profits, which would be subject to conditions they established. And they add that this incentive would be outside the collective convention," the statement from Minera Panama Workers Union said in Spanish on Thursday, adding that the company has not offered anything new except a "penny increase."

"The current situation of stagnation has been caused by the company and its false promise that its latest proposals would be the best ... but they came out with the worst. The strike is maintained for next Saturday, April 9 from noon," the statement added.

First Quantum did not immediately respond to an email query from Reuters on whether it has made a new offer to the union.

Shares of First Quantum were down 2.4% on Friday on the Toronto Stock Exchange.