"The situation is absolutely critical ... The dams have never been so empty since their construction years ago," TANESCO Managing Director Adriaan van der Merwe said in a statement late on Thursday.

TANESCO started rationing electricity for eight hours a day early this month after months of erratic supply in the commercial capital.

The drought across eastern Africa is already threatening at least 6 million people with famine, and the power cuts are one of the first signs of what many say will be its widespread cost to the region's economy.

Neighbouring Kenya, the region's biggest economy, said on Friday that it could face "massive power rationing" by June if water levels at its crucial Masinga power dam kept falling at their current rate.

The Energy Ministry in a statement said the country would be installing up to 180 megawatts (MW) of emergency generation starting in April, anticipating a power shortfall through as late as February 2007.

In Tanzania, the TANESCO statement gave no details on how many more hours of rationing would be added and the company did not answer calls seeking comment.

The utility plans to buy gas turbines from Bermuda-based power company Globeleq in April and is now running diesel generators, a costly proposition because of high oil and spare part prices, van der Merwe said.

Tanzania's total generation capacity is 953 MW, of which more than two-thirds is hydroelectric.

The east African country will have difficulty buying extra power from Kenya and Uganda, since Kenya's hydropower plants are facing shortages of their own and Uganda has to import power.