Congo's mineral-rich Katanga province cleared nine companies to resume cobalt concentrate exports on Friday, but extended a 3-week-old ban on others pending upgrades to their treatment plants, an official said.

A team of experts brought in to inspect processing plants completed its report on Friday and gave a green light to those companies that met criteria set by the provincial government, Provincial Mines Minister Bartelemy Mumba Gama said.

We took into account the supply source, treatment technology, and the longevity of projects, Mumba Gama told Reuters by telephone from the provincial capital Lubumbashi.

There are companies that must improve their systems. Then perhaps they will be able to export again.

Katanga Governor Moise Katumbi halted exports of cobalt concentrate on May 15, saying mining companies were flouting a year-old ban on exporting raw ore.

Hundreds of small mineral buyers have appeared in Katanga's copper and cobalt belt, as the end of a 1998-2003 war and 2006 elections returned a measure of stability to Congo.

Most purchase ore from the tens of thousands of informal diggers that invaded concessions during the war years.

Congo closed facilities belonging to Congo Dongfang International Mining, a subsidiary of China's Zhejiang Huayou Cobalt Co., last month, accusing it of breaking the ban on exporting raw ore.

Kamoto Operations Limited and DRC Copper and Cobalt Project, both operations belonging to Katanga Mining Ltd were among those companies approved to restart exports.

Boss Mining, Chemaf, Metorex Limited's Congolese subsidiary Ruashi Mining as well as Anvil Mining Limited's AMCK and SMK projects were also cleared by the experts. (Reporting by Joe Bavier; editing by Alistair Thomson and Peter Blackburn)

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