* Congo is Africa's top copper producer
* Katanga mine is one of country's largest
* Collapsed wall was more than 250 metres high (Recasts with toll, adds quote, context)
By Kenny Katombe
KOLWEZI, Democratic Republic of Congo, March 8 (Reuters) - T wo workers at Glencore's huge Katanga Mining copper and cobalt operation in southeastern Democratic Republic of Congo died on Tuesday and five remain missing, the mine's chairman said after a 250-metre pit wall collapsed.
"Of the seven who disappeared, two bodies were found," Gustave Nzeng, chairman of Kamoto Copper Company (KCC), the joint venture that runs the mine, told reporters in the town of Kolwezi.
Rescue efforts to find the remaining workers were being hindered by heavy rain, Nzeng said.
Mining companies in Congo extracted just under 1 million tonnes of copper in 2015, making the country Africa's top producer.
Major companies such as Freeport-McMoRan, Ivanhoe and Eurasian Natural Resources Corporation have invested heavily in the sector since a 2003 peace deal drew a line under years of regional war in Congo's east that killed millions, mostly from hunger and disease.
Deadly accidents are common in Congo's mostly unregulated artisanal mining sector, where diggers use rudimentary tools, but far rarer at its large industrial mines.
The Katanga Mining joint venture is controlled by Glencore, the Swiss-based mining and trading company, while Congo's state mining company Gecamines and Israeli billionaire Dan Gertler's Fleurette Group both hold minority stakes.
The project is one of the country's largest and consists of both underground and open-air mines formerly owned by Gecamines. It started commercial production in 2008.
Katanga Mining announced an 18-month suspension of production last September, but work on maintenance and an $880 million modernisation project to cut costs has continued.
Delphin Monga, provincial secretary of the UCDT union, which represents KCC workers, said that many more workers would likely have been killed had it not been for the suspension.
"This was the least bad scenario because there weren't nearly as many workers there as before," Monga said.
Richard Muyej, the top government official in Lualaba province, told Reuters that the wall that collapsed in the KOV open pit mine was more than 250 metres high.
The landslide was also believed to have damaged drainage equipment in the pit, Glencore said in a statement. (Additional reporting and writing by Aaron Ross in Kinshasa; Editing by Matthew Mpoke Bigg and David Evans)