Italian Prime Minister Silvio Berlusconi's government is being tested again as Italians cast votes in four referendums, including one that would end plans to restart the country's nuclear energy program.

The two-day referendums began Sunday. The most emotive issue concerns Mr Berlusconi's plan to restart nuclear power plants, which he proposed last year but then put on hold following the nuclear disaster at Japan's Fukushima plant in March. Italy's nuclear plants were shut down in 1987 after a similar referendum.

Opinion polls say the majority of Italians are against nuclear energy, but in order for the referendum to be valid, more than 50 percent of eligible voters must cast ballots.

In a second referendum, voters will decide whether to reject a law exempting government ministers from attending trials against them. Two other referendums involve plans to privatize Italy's water utilities.

For some, the referendums will be a way for voters to express their disappointment at Mr. Berlusconi, whose government is stinging from heavy losses in local elections last month. The Italian leader is a defendant in several ongoing trials for fraud as well as for allegedly having sex with a 17-year old prostitute.