The city of Tsuruga, Fukui Prefecture, will not give the go-ahead to renovate the trouble-plagued Monju fast-breeder reactor prototype until after the Supreme Court clears it of nuclear safety concerns, Mayor Kazuharu Kawase said Monday.

The move comes in the wake of the central government's decision Friday to appeal a Nagoya High Court decision nullifying its 1983 approval to build the plutonium-producing reactor in the city.

While expressing disappointment with the high court ruling, Kawase said the city may not be able to host the reactor if the top court judges that it poses significant safety threats, suggesting a delay in local approval.

The reactor began operations in August 1995, but was shut down after a sodium coolant leak sparked a fire in December that year.