The discovery of possible cracks in a Belgian nuclear reactor should trigger urgent testing around the EU, but such decisions are for national governments to take, a European Commission spokeswoman said on Thursday.
"National authorities will conduct tests, that seems obvious," said Marlene Holzner, spokeswoman for EU energy commissioner Guenther Oettinger. "The European Commission can make recommendations, but it can't make them binding," she stressed.
Belgium's federal agency for nuclear control, AFCN, said on Wednesday that the Doel 3 reactor, located 25 kilometres (20 miles) north of Antwerp, would remain closed at least until August 31 after the discovery of possible cracks during routine June testing.
The agency is also mulling the permanent closure "in the worst case" of a second reactor in the country's south near Liege, also produced by now-defunct Dutch firm Rotterdam Drydocks.
As well as the two Belgian reactors, French daily Le Monde said another 10 went to the United States, two each to Germany, the Netherlands, Spain and Switzerland, plus another one each in Argentina and Sweden.
Holzner said final results from EU-supervised stress tests on nuclear plants, ordered in the wake of last year's Japan earthquake and damage to a reactor in Fukushima, had been delayed because of concern that "not all types of reactors have been tested on the ground."
The EU in total counts 147 reactors in 14 countries -- more than a third of the total in France, which depends almost entirely on nuclear generators for electricity.
Only 38 of the 147 had so far been tested.
Holzner reiterated that EU headquarters must rely on national authorities.
"It is their responsibility, not ours, to act -- to shut down or also to improve the technology," she said.
Belgium recently said it would aim for a phased exit from nuclear energy between 2016 and 2025, with Doel 3 originally set to shut for good in 2022.