European Union officials Thursday defended sending out the first EU-wide nuclear safety alert after a minor leak at a Slovenian power plant, saying the public needed to know, according to dpa. The UN International Atomic Energy Agency rated Wednesday's leak and shutdown at the Western-built Krsko plant as the least dangerous on its emergency scale - not even an "incident." But the European Commission, the EU's executive arm, triggered its first-ever nuclear safety alert to all 27 EU nations under a system set up after the 1986 Chernobyl disaster in Ukraine. Slovenia added to the confusion, first mistakenly telling its neighbours the incident was a mock emergency for a safety drill, then informing European authorities that it was for real. Politicians in neighbouring Austria criticized the bungle. Although minor, the incident revived debate over nuclear power on a continent where many question its safety, especially in eastern European plants. It also came at a time when nuclear power is increasingly hailed as a way to cut down on greenhouse gases. In Brussels, EU spokesman Ferran Tarradellas praised Slovenia for reporting the incident, calling it "a good example of transparency in the case of a nuclear event." It was "the best way to reassure citizens," and from now on the Commission will inform the public "each time there is such an incident as this one," he said. Plant operators shut down Krsko's single 696-megawatt reactor Wednesday within about two hours of a leak in the primary cooling system, which keeps the reactor core from overheating. No radioactivity was released and repairs at Krsko - built by US- based Westinghouse and jointly owned by Slovenia and Croatia since 2002 - were to start Thursday after the reactor cools down, Slovenian officials said. Slovenia's government suggested the EU warning, which asks member countries to consider possible public safety measures, went too far. "The message could have been understood as a warning of an incident with the possibility of serious consequences," Slovenia's Environment Ministry said in a statement. An official at the country's Nuclear Safety Administration, Marjan Tkavc, said Slovenia itself overreacted. "Yes, we were too hasty to report the incident in Krsko to the European early-warning system as dangerous," he told Deutsche Presse- Agentur dpa. Krsko, begun in 1974 and online since 1982, is former Yugoslavia's only commercial nuclear power plant. In 2003, a defective valve forced a shutdown that brought Slovenia, a nation of 2 million, to the brink of an electricity collapse. Slovenia has tentative plans to build a second reactor at the site near the Croatian border. The latest mishap came just as Slovenia wraps up its six-month EU presidency. In Austria, where voters narrowly rejected nuclear power in a 1978 referendum, politicians demanded an investigation and renewed calls for Krsko to be shuttered. "We have to find out as quickly as possible how this confusion in the information came about," Austrian Environment Minister Josef Proell told reporters at an EU ministers' meeting in Luxembourg. "To set off a European alert and then tell Austria, Italy and Hungary it's an exercise - that requires an explanation," he said. Croatian media featured angry headlines, saying residents were informed about the incident only after three hours, although Krsko is just 30 kilometres away from the capital Zagreb. "Croats were the last to find out" and "Krsko is a permanent threat to Zagreb," newspaper headlines said. Nuclear safety is a highly sensitive subject in the EU, after several member states - notably Italy and Germany - phased out nuclear power or plan to. Bulgaria bowed to EU demands and shut down four Soviet-era nuclear reactors at Kozloduy by 2006, leaving it with two modern, 1,000- megawatt Russian-built generators. Another former Communist-bloc EU state, Lithuania, is due to shut down the Soviet-built Ignalina nuclear plant by the end of 2009. Krsko is due to remain online until 2023. After decommissioning, the plant reportedly would be dismantled by 2036.