LUSAKA, Oct 8 (Reuters) - Copper-rich Zambia suffered a major power outage affecting most parts of the country on Friday after a problem at an important hydropower station, and the state utility said it was working to restore supply. "There has been loss of generation at Kariba North Bank hydropower station and this has affected supply to a large geographical area of the country," said spokesman John Kunda of state-owned power company Zesco. Residents in the capital Lusaka as well as Kitwe and Ndola in the copper belt said they were without power. Kunda said Zesco was "rebooting the system" but that it could take three to four hours before supply was fully restored.Konkola Copper Mines (KCM) said in a statement that its mines, tailings leach plant and Nchanga smelter were affected by the blackout. "Emergency generators have been switched on to stabilise operations at the smelter and the Tailings Leach Plant. ... Flood gates have been activated and closed at Konkola underground mine, while we have shut boreholes underground to limit the flow of water into the mine and avert flooding," KCM said.