A temporary administrator appointed by a Congolese court to run the world's second-largest cobalt mine ordered majority owner CMOC to suspend marketing and export of its production, letters seen by Reuters showed.

CMOC, which has previously said that Tenke Fungurume Mining (TFM) remains under its management, did not immediately reply to a request for comment on the letters dated June 29 and July 1.

The order is the latest escalation in a dispute between CMOC, which owns 80% of TFM, and Democratic Republic of Congo's state mining company Gecamines, which holds the remaining 20%.

Congo's government says it suspects CMOC understated reserve levels to reduce the amount of royalties it pays to Gecamines. CMOC, which was previously known as China Molybdenum, denies having done so.

Gecamines and Congo's mines ministry were not immediately reachable for comment. It was not immediately clear whether TFM's exports were still being let through the border.

In the June 29 letter, addressed to CMOC's board, the provisional administrator wrote that the terms for the marketing of TFM's production in 2022 had not been met, and ordered CMOC to share all the information purporting to its marketing and exports since January 1 within 24 hours.

The letter ordered CMOC to stop marketing and exporting product from TFM in the interim.

In the July 1 letter, the provisional administrator ordered Congo's customs authority to implement the suspension of TFM's exports.

In an interview with the China Global South Project's French-language publication on Monday, China's ambassador to Congo said the Chinese government is closely following the dispute between Gecamines and CMOC and "making sure the rights of Chinese companies are respected".

"We must encourage the two companies to maintain a dialogue... without using the apparatus of the state or resorting to brutal methods," Ambassador Zhu Jing said.

TFM produced 18 501 tonnes of cobalt and 209 120 tonnes of copper in 2021.