(Recasts with union comment)
By Chris Mfula
LUSAKA, Sept 1 (Reuters) - Thousands of miners in Zambia may lose their jobs due to power supply problems and sinking copper prices, the head of the country's largest mining union said on Tuesday.
Erratic electricity supplies have hit the mining industry in the southern African nation, the continent's second biggest copper producer, where the bulk of electricity is water-powered.
Meanwhile the price of copper is at six-year lows, weighed on by an economic slowdown in China, one of the world's biggest consumers of metals and other raw materials.
"Some of our members have already been told that they will either be sent on forced leave without pay, recess, which means they stay home on full pay to avoid paying them other expenses like over-time allowance or outright retrenchment," Nkole Chishimba, president of the Mine Workers' Union of Zambia told Reuters, without naming the firms.
Chishimba said the government should urgently call for a meeting with mining companies and the trade unions to discuss the looming jobs cuts. The MUZ represents about 25,000 workers, he said.
Zambian state power utility Zesco Ltd said on Tuesday it will deepen power cuts after water levels at its largest hydro power station dropped following a drought, potentially affecting mining.
"Power generation at Kariba North Bank power station has been reduced to 305 megawatts from 540 megawatts," Zesco spokeswoman Bessie Banda said.
"The idea is for us to conserve water and continue generating power until the next rainy season."
The government would procure emergency power from September onwards into 2016 and Zesco has been importing electricity from Mozambique and the Southern African Power Pool, Banda said. She did not say when emergency power procurement would end in 2016.
Zambia's largest supplier of power to mines, Copperbelt Energy Corp, is also experiencing severe power shortages and has had to limit electricity supplies to big mining firms including Vedanta Resources and Glencore .
Canada's First Quantum, whose power is supplied by Zesco, said last month it would cut thousands of jobs after the reduction in electricity supply curbed production.
Most other countries in southern Africa, including South Africa, Botswana and Zimbabwe are also grappling with power supply shortages.
Zimbabwe's power utility said on Tuesday its two biggest electricity generation plants will start annual routine maintenance on Tuesday, leading to even deeper power cuts. (Editing by James Macharia and Greg Mahlich)