Bojan Kumer, the minister of environment, climate and energy, has sparked controversy by saying there will be nothing wrong if the timeline for a new unit at Slovenia's sole nuclear power station is delayed.

In an interview run by the news portal N1 last weekend, Kumer discussed delays in the project known as NEK2, after the acronym for the Krško Nuclear Power Station (NEK). He admitted changes in the timeline, adding there "will be nothing wrong, if it is delayed".

His ministry plans to submit an update to the NEK2 planning application, requested in September 2022 by what was formerly the Ministry of Environment and Spatial Planning, "in the coming months".

Kumer did not disagree with the observation that the government has been devoting more attention to renewable energy sources and is also counting on new technologies.

He referred to the fast progress of small nuclear reactor technology: "If it keeps up this momentum, it can replace mature technology, that is conventional nuclear reactors, within two years," he said.

Janez Janša, the leader of the largest opposition party and former prime minister, denounced Kumer's comment about delays in the NEK2 project on Twitter as one that merits criminal prosecution and holding the government liable for damages.

The NEK2 timetable was adopted under the Janša government amid vocal support for nuclear energy.

Jernej Vrtovec, an MP for New Slovenia (NSi) who served as infrastructure minister in the Janša government, has now called a session of the parliamentary Public Finance Oversight Commission, which he chairs, to discuss the government's "dragging its feet" over construction of the new unit at Krško.

Addressing reporters on 15 March, he expressed concern about the country's energy independence and green transition amid a global energy crisis.

As Slovenia wants to become climate-neutral by 2055, Vrtovec argues the key will be nuclear energy, which was also recognised as sustainable by the European Commission in February 2022.

The Krško N-plant provides 25% of the country's electricity. Given that its operating licence ends in 2043 and that Slovenia wants to phase out coal, meaning shut down the Šoštanj Thermal Power Station by 2033, the question arises how to compensate for such large shortfalls.

Renewables alone will not do, Vrtovec said.

The previous government issued an energy permit for NEK2 in 2021 and launched zoning procedures in 2022. However, Vrtovec is worried about the future timeline considering the lengthy spatial plan, building permit and cross-border evaluation procedures.

He noted that Austria is opposed to nuclear energy, and that it takes five to six years to build a nuclear plant.

He feels that national spatial plan procedures for the plant seem to have come to a halt under this government and that solar energy is being prioritised.

Tina Seršen, a state secretary at the Ministry of the Environment, Climate and Energy, described Vrtovec's claims as exaggerated.

Judging by experience, Seršen said the construction of NEK2 would take 15 years in the best-case scenario, while Slovenia already has an energy problem - during the coal production shortfall least year, the country depended on imports for 30% of its energy needs.

She disagrees with Vrtovec's view that Slovenia would not be able to rely solely on renewables. "We can't know this yet without serious expert analyses at a national level. We're conducting these now and they will show how we can achieve our climate goals," she said.

The National Energy and Climate Plan, which is to answer those questions, is to be presented by the summer.

Seršen rejected the claim the ministry was dragging its feet, arguing the previous government had been sloppy in preparing the project, committing "mistakes we cannot afford when the biggest investment in the country's history is at stake".

She argued the cost of the project would exceed the largest ones to date by at least five-fold.

The state secretary said the ministry was working hard on the project so as to get a realistic timeline. She confirmed a referendum would be held on the project.

"I imagine that people want to make informed choices about what is going to be built, for how long, how much it will cost, what the consequences will be, what the final price for the consumer will be, who is going to build it. We still need to explore all this. It takes time, without these answers we cannot go before the people and credibly talk about the pros and cons," she said.

Danijel Levičar, managing director of Gen Energija, which runs the Slovenian half of the Krško Nuclear Power Plant, said earlier this week NEK2 could be up and running by 2035 if all went well.

He said that most recent polls showed about 55% of Slovenians supported the project.