"Due to today's earthquake, the Nuclear Power Plant of Krsko automatically shut down and is in a safe shutdown mode," a statement on the plant's website said, adding that checks would be performed on its systems and equipment.

Infrastructure Minister Jernej Vrtovec said that the plant should be reconnected to the electricity network within 24 hours, according to the STA agency.

The earthquake was felt in several neighbouring countries, including Slovenia and as far away as the Austrian capital Vienna.

A session of parliament in Slovenia had to be suspended and light damage to buildings was reported in the east of the country, as well brief interruptions to electricity networks.

Krsko is Slovenia's sole nuclear power plant and lies about 100 kilometres (60 miles) east of the capital Ljubljana.

The 700-megawatt Westinghouse reactor was built in the former Yugoslavia and went into service in 1983.

It is co-owned by Slovenia and Croatia.

The plant provides for around 20 percent of Slovenia's electricity needs and 15 percent of Croatia's but environmental campaigners have previously called for it to be shut down because of its age and the risks of seismic activity in the region.

It was originally due to be switched off in 2023, but Ljubljana and Zagreb decided in 2015 to extend its lifetime by another 20 years.