BEIJING/SHANGHAI/SINGAPORE/LONDON - China's top copper producers are seeking to add new members to an industry price-setting group, four sources with knowledge of the matter said, in a bid to strengthen their position in negotiations with miners over raw material supply.

The China Smelters Purchase Team (CSPT), a group of 16 major producers that traditionally sets floor prices for spot copper concentrate processing deals, invited at least six prospective new members to attend its quarterly meeting in Yantai in Shandong province on Wednesday, a fifth source said.

Expanding the CSPT to include most of the country's smelters could help producers leverage China's position as the world's largest copper consumer to win better deals from miners. A similar logic is driving China's increasingly confrontational negotiating tactics in the iron-ore market.

The companies invited to the CSPT gathering include Guangxi Nanguo, Chizhou Guanhua, Xinjiang Wuxin, Bayannur Feishang, Chifeng Fubang and Yanggu Xiangguang, two of the sources said.

Their admission to the group is not yet set in stone, as they need to be incorporated via a formal process, the fifth source said.

SPOT TREATMENT AND REFINING CHARGES IN NEGATIVE TERRITORY

Chinese copper smelters are in the middle of negotiations with Chilean miner Antofagasta over concentrate supply deals. Miners usually pay treatment and refining charges (TC/RCs) to smelters to process their ore into refined metal.

However, owing to a shortage of concentrate supply, spot TC/RCs have been deep in negative territory for months, leaving smelters effectively having to pay to process material, relying on sales of byproduct sulphuric acid to make money.

TC/RCs typically fall when concentrate supply is tight and rise when ore availability improves.

During the meeting, the CSPT declined for the sixth straight quarter to issue quarterly guidance for TC/RCs, the sources
added.

CHINA'S REFINED COPPER OUTPUT STILL GROWING

Whether an expanded CSPT can help win better terms remains to be seen given the group's mixed track record corralling the industry. Last year it committed to cut 2026 copper output by 10%, but so far the opposite has happened.

China's refined copper output grew 7.4% between January and April from the same period of last year, according to the
latest data from the National Bureau of Statistics.

Reuters sent emailed requests for comment to C&D Inc, which controls Yanggu Xiangguang, a 400 000 ton-a-year smelter, and to Xinjiang Nonferrous Metal Group, which owns Xinjiang Wuxin. They did not immediately respond.

Calls to Guangxi Nanguo and Chifeng Fubang went unanswered. Reuters could not immediately find contact details for Bayannur Feishang or Chizhou Guanhua.