The nuclear power plant in Tihange, Belgium, is one of two in the country that Germany has asked to be temporarily shut down due to safety concerns

Germany asked neighbouring Belgium on Wednesday to temporarily shutter two ageing nuclear plants near their border over safety concerns.

Environment Minister Barbara Hendricks requested that the 40-year-old Tihange 2 and Doel 3 reactors be turned off "until the resolution of outstanding security issues".

The reactor pressure vessels at both sites have shown signs of metal degradation, raising fears about their safety. They were temporarily closed but resumed service last December.

The reactor at Tihange is located just 60 kilometres (40 miles) from the German border, while Doel is about 130 kilometres away, and close to Antwerp.

Hendricks pointed to a report by a German advisory body, the Reactor Safety Commission (RSK), and discussions between German and Belgian experts.

"The independent experts of RSK cannot confirm that the safety margins of Tihange 2 and Doel 3 can be maintained," she said in a statement.

"That is why I believe it is right to temporarily take the plants off-line, at least until further investigations have been completed."

Such a step would be "a strong precautionary measure" and "would show that Belgium takes the concerns of its German neighbours seriously," she said.

Belgium's creaking have been causing safety concerns for some time after a series of problems ranging from leaks to cracks and an unsolved sabotage incident.

The Doel and Tihange power stations have been in service since 1974-1975, and were scheduled to be shut down in 2015.

But the Belgian government in December decided to extend their lives to 2025, under a deal to preserve jobs and invest in the transition to cleaner energy.

Germany—where the public mood swung against following the 1986 Chernobyl disaster—decided after Japan's Fukushima meltdown five years ago to phase out nuclear power by 2022.

Germany in early March also demanded that France close down its oldest nuclear plant, Fessenheim, located near the German and Swiss borders, over safety concerns.