Several hundred objections have been handed in against an unlimited operating licence for the Mühleberg nuclear power plant near the capital, Bern.
The Federal Energy Office said the exact number of objections was not yet known but one had come from the centre-left Social Democratic Party.
A lawyer commissioned by the Fokus Anti-Atom organisation drew up the party's collective objection, which included a number of individuals and groups.
Opponents say the energy ministry should not even consider the request made by the BKW energy company, which is based in Bern, arguing that some safety demands had not been met.
BKW made its formal application to waive the time limit on the operating permit at the beginning of 2005, arguing that Mühleberg was the only nuclear plant in Switzerland without an unlimited permit.
The company says that since the plant was commissioned at the end of 1972, it had made a "significant contribution towards secure, reliable and environmentally friendly power supply in western and northwestern Switzerland."
BKW adds that the plant is fully compliant with the technical requirements for safe continued operation over the next ten to 20 years. The current permit expires at the end of 2012.
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