Burundi said on Wednesday its reserves of nickel were about 4,2-million tonnes, which should allow for exploitation over half a century.
But Mines and Energy Minister Samuel Ndayiragije told Reuters in an interview that mining of the metal could not start for five years due to insufficient energy.
After that, "research studies showed that our nickel could be exploited in a period of 50 years", he said.
The minister said the central African nation needed between $300- and $400-million to build a 60-MW-capacity hydroelectric dam to power nickel exploitation.
That is nearly double national capacity of 32,5 MW.
The government has already presented the energy project to World Bank and African Development Bank.
"Nickel research and exploitation is not an easy task and it takes a long time. This is the reason why we need support from donors," the minister said.
Burundi has three nickel deposits in the southeast and central parts of the country. The authorities have so far issued six research permits to multinational miners.
Officials say nickel resources could transform Burundi's economy, which now relies mostly on coffee and tea exports.