Yunnan Tin had in June flagged deeper cooperation between its ultimate controlling shareholder, the Yunnan branch of the State-owned Assets Supervision and Administration Commission (Sasac), and Minmetals that could have brought a change in the ownership of the company.

A potential merger of the two firms was expected to be completed by October this year, the International Tin Association (ITA) said later in June, citing local sources.

But "in view of the failure of the relevant parties to reach agreement on specific cooperation matters," the discussions have been terminated, Yunnan Tin said in a filing to the Shenzhen Stock Exchange.

Minmetals did not immediately respond to a request for comment. The diversified miner, which already produces copper, lead and zinc and trades tin, would have added tin production to its metals portfolio with the move.

Yunnan Tin produced 77,789 tonnes of refined tin in 2018 - more than double the output of nearest rival PT Timah, according to the ITA, but pledged to cut its output by 10% this year in a pact with other producers to prop up falling prices.

A merger would also have marked the second time in two years a central government-run Chinese metals firm had taken control of a major Yunnan producer, after Aluminum Corp of China, or Chinalco, took over Yunnan Metallurgical Group - and in the process Yunnan Aluminium - in 2018.

Kunming-based Sino-Platinum Metals, which also flagged a potential change in its controlling shareholder in June, likewise said it had been informed by Yunnan Sasac that the talks on deeper cooperation with Minmetals had been terminated.

(Reporting by Tom Daly, editing by Louise Heavens)