A diesel shipment under a $500 million credit line from neighbouring India is expected to arrive on Saturday, Wanniarachchi said, but she warned that the situation was not likely to improve any time soon.
"Once that arrives we will be able to reduce load shedding hours but until we receive rains, probably some time in May, power cuts will have to continue," Wanniarachchi told reporters, referring to the rolling power cuts.
"There's nothing else we can do."
Water levels at reservoirs feeding hydro-electric projects had fallen to record lows, while demand had also hit record levels during the hot, dry season, she said.