The application, which was filed on Monday, represents a new phase in which French authorities will examine the plan for safety to ensure it guards against radioactive leaks.

The project, called Cigéo, calls for the waste to be stored 500 metres below ground in the Callovo-Oxfordian clay formation in eastern France. Currently the waste is temporarily stored on the surface, the agency said.

Construction could begin as soon as 2027 if the French nuclear safety authority approves the application.

Authorisation for an industrial pilot phase to store some waste could come from 2035 to 2040, with full operational approval between 2040 and 2050, the agency said.

Finland, Sweden, Switzerland, Belgium and the Netherlands are also examining the construction of long-term high-level radioactive waste storage sites.

Andra, the nuclear waste treatment agency, said this latest application for the storage site did not include the six new EPR nuclear reactors currently under consideration for construction by French power giant EDF, citing the lack of a final decision to embark on the new build.

Pierre-Marie Abadie, director general for Andra, said that the agency has in the past published a report saying waste from six new nuclear reactors could be encompassed in the future storage project "without difficulty."

(Reporting by America Hernandez, editing by Silvia Aloisi and Louise Heavens)