HARARE, Dec 20 (Reuters) – Zimbabwe has imposed a ban on the export of unprocessed lithium, according to a government notice seen by Reuters on Tuesday, in a bid to stop artisanal miners who the government says are digging up and taking the mineral across borders.

The southern African country holds some of the world’s largest reserves of hard rock lithium, a vital mineral in the production of clean energy technologies.

Chinese giants Zhejiang Huayou Cobalt 603799.SS, Sinomine Resource Group 002738.SZ and Chengxin Lithium Group 002240.SZ have over the past year acquired lithium mines and projects worth a combined $678 million in Zimbabwe and are at various stages of developing mines and processing plants, which would exempt them from the ban.

London-listed Premier African Minerals PREM.L says it will start shipping spodumene concentrate from its Zimbabwe lithium mine to China from March 2023, after signing an offtake deal with Suzhou TA&A Ultra Clean Technology Co 300390.SZ.

“No lithium bearing ores, or unbeneficiated lithium whatsoever, shall be exported from Zimbabwe to another country,” read the regulation published in a government notice issued by Mines Minister Winston Chitando.

The notice said the ban does not apply to the export of lithium concentrates, which all the major lithium miners in the country plan to produce.

President Emmerson Mnangagwa has previously said the ban would target hordes of artisanal miners, who were drawn by the mineral’s high prices and invading abandoned mines to dig for lithium-bearing rocks. Mnangagwa said the raw lithium was being exported through neighbouring countries.

(Reporting by Nelson Banya, editing by Deepa Babington)