Slovenia's only nuclear power plant resumed energy production on Tuesday after a preventive shut down as the Sava river -- which is used to cool down the plant -- was clogged up by leaves and rubbish.

"The Krsko nuclear power plant was connected to the energy network after all the equipment's check-ups were carried out and the situation was evaluated," the operator of the Krsko nuclear plant, located some 90 kilometres (55 miles) east of the capital Ljubljana, said in a statement.

The plant's production was stopped manually on Sunday over fears that the clogged up Sava river would impact the efficiency of the plant's cooling system.

But during the shutdown, the plant's systems and equipment were found to be functioning well.

The nuclear plant -- jointly built with Croatia in 1984 when they were both part of the former Yugoslavia -- accounts for about 40 percent of the EU country's electricity production.