BEIJING (Reuters) - A gun attack in a mining area in the Democratic Republic of Congo (DRC) has killed three Chinese nationals, China’s official Xinhua news agency reported on Monday, citing the Chinese embassy in the mineral-rich central African country.

The attack took place on Saturday in the northeastern province of Ituri, which borders Uganda and South Sudan, Xinhua said, without naming the mine in question or the company operating it. “Three Chinese citizens were unfortunately killed,” it added.

The DRC is the world’s biggest producer of mined cobalt - a key ingredient in batteries for electric vehicles - and one of Africa’s biggest copper producers, although its key copper-cobalt producing region is in the southwest, far from the site of the attack.

The country has attracted billions of dollars in investment from Chinese miners in recent years despite security risks. Canadian gold miner Banro, which owns mines in Maniema, a DRC province south of Ituri, suspended operations last year after several of its mines were overrun by armed rebels.

The Chinese embassy has asked the Congolese government to “take effective measures to protect the lives and property of Chinese citizens” in the DRC, as well as to expedite an investigation into the killings, Xinhua said, noting that the embassy had repeatedly advised Chinese citizens against travel to Ituri due to the presence of armed groups.

The embassy did not immediately respond to an e-mailed request for comment on Monday, a public holiday in China.