European Energy Commissioner Guenther Oettinger says almost all of the EU’s nuclear reactors need around £20bn of safety improvements.
The European Union today released a report following stress tests carried out in the wake of the March 2011 Fukushima accident in Japan.
Officials said earlier that the tests did not reveal the need to close any plants immediately.
EU leaders agreed last year to put the reactors through the toughest security checks possible to gauge their ability to withstand accidents and natural disasters.
The EU said the tests had established that not all safety standards promoted by the International Atomic Energy Agency (IAEA) and not all international best practices were being applied in all member states. The European Commission would follow closely the implementation of the recommendations and would at the same time propose legislative measures to further enhance nuclear safety in Europe.
Oettinger said: "The stress tests have revealed where we are good at and where we need to improve. The tests were serious, and they were a success. Generally, the situation is satisfactory but there is no room for complacency. All authorities involved must work to ensure that the highest safety standards are in force in every single nuclear power plant in Europe. For the safety of our citizens".