A drought in Serbia has pushed the Danube river to a record-low level, forcing the country to significantly reduce electricity generation from its main hydroelectric plants, the Balkan country's energy minister said Sunday.

The two biggest plants, Djerdap I and Djerdap II, have been reduced to an output of just 20% and 30% of their respective capacities, Dubravka Djedovic Handanovic told state RTS television.

The facilities provide around 18% of Serbia's electricity generation.

Hydroelectric power accounts for nearly a third of Serbia's energy mix, with thermal plants making up the rest.

But with the Danube hitting historic lows in some areas because of waves of extreme hot weather sweeping Europe since May, their operations have suffered.

Serbian meteorologists say there has been no significant rainfall to feed the river for the past five or six weeks.

Neighboring Hungary is facing similar energy-production challenges, with the prime minister announcing on Sunday the shutdown of the country's only nuclear power plant, which is also dependent on the Danube for cooling.