(Update 2pm EST)

KINSHASA, June 27 (Reuters) - At least 39 artisanal miners were killed on Thursday when part of a copper and cobalt mine owned by Glencore collapsed in southeast Congo, the provincial governor said.

The accident occurred in the KOV open-pit mine at the Kamoto Copper Company (KCC) concession, in which Glencoresubsidiary Katanga Mining owns a 75% stake, said Richard Muyej, the governor of Democratic Republic of Congo's Lualaba province.

"It was caused by the clandestine artisanal diggers who have infiltrated (the mine)," he told Reuters. "The old terraces gave way, causing significant amounts of material to fall."

"KOV is a delicate site and presents many risks," he added.

Glencore said in a statement that it had confirmed 19 fatalities so far and was assisting search and rescue operations by local authorities.

The statement said an average of 2,000 illegal miners sneak onto KCC property each day. The rudimentary and often outdated practices employed by artisanal miners can compromise the safety of the mines, and accidents among them are common.

Delphin Monga, provincial secretary of the UCDT union which represents KCC employees, said a crack in that part of the pit had been noticed on Wednesday. He said KCC had put up red warning signs, but the diggers had ignored them.

The KOV mine, which spans a vast flat expanse on the outskirts of the city of Kolwezi near the Zambian border, is one of the largest high-grade copper assets in the world.

The collapse of a 250-metre wall inside the same pit killed seven mine employees in 2016.

Thousands of illegal miners operate in and around mines in southern Congo, which produce more than half of the world's cobalt, a key component in electric car batteries.

Mine disasters in Africa have cost the lives of numerous miners, especially unauthorised artisanal miners who operate without safety standards or regulations.

At least nine illegal gold miners died in Zimbabwe when they were trapped in a mine last month.

Twenty-two died in a previous Zimbabwean gold-mine flood in February, and 14 tin miners were buried alive in Rwanda after heavy rains in January.

In February, about 20 people died when a truck carrying acid to Glencore's Mutanda Mine in DRC collided with two other vehicles.

Shares in Glencore closed down 4.9%, their worst day of trading since December. The company said the incident has not affected output.

BMO Capital Markets analyst Edward Sterck said if the incident is related to illegal mining, any impact may be relatively short-term beyond an investigative period.

"However, preventative action will likely be needed and it could impact Glencore's social licence to operate," he added.

Congo’s military hasd deployed hundreds of soldiers last week to protect a major copper and cobalt mine owned by China Molybdenum Co Ltd from illegal miners, an army spokesman said on Wednesday.

The Tenke Fungurume mine is one of the largest in Democratic Republic of Congo, which is Africa’s leading copper producer and the world’s top miner of cobalt, a key component in electric car batteries.

Mining companies operating in Congo, which include Glencore, Ivanhoe and Barrick, routinely say the presence of illegal miners on their properties is one of their greatest challenges. As many as 10,000 diggers have been estimated to operate in and around the Tenke mine.

The army deployed several hundred troops on Tuesday to the Tenke mine, spokesman Colonel Emmanuel Kabamba said.

“The hierarchy decided to deploy soldiers to secure the company because the company contributes to the economy of this country,” Kabamba told Reuters.

China Molybdenum did not immediately respond to a request for comment.

The watchdog group Southern African Resources Watch (SARW) said in a statement that the deployment was “dangerous and potentially counterproductive”.

“The deployment of soldiers, if not well managed, risks leading to unfortunate human rights abuses, which could tarnish the reputation of the company and the supply chain for Congolese cobalt,” it said.

Previous army deployments to Congolese mines have generated controversy. Government troops killed scores of civilians in 2004 in the copper-mining town of Kilwa as they battled a small group of ill-equipped rebels.

Nine Congolese soldiers were tried for war crimes and three employees of Australia’s Anvil Mining were tried for complicity in war crimes over the killing A military court acquitted them all in 2007.

The electric vehicles revolution has fueled rising demand for cobalt, but human rights groups have raised concerns about a supply chain they say is tainted by child labor and other human rights abuses.