The Swiss government has launched an appeal of a court decision seeking the early closure of the aging Muehleberg nuclear power plant near Bern.

A ruling this month by the Federal Administrative Court determined that the Department of the Environment, Transport, Energy and Communications should revoke the plant's operating license by June 2013 on safety and security grounds.

The court's ruling ordered the ministry to revoke the plant's license in the absence of a comprehensive maintenance plan by plant operator, BKW.

The decision brought cheers from nuclear energy opponents but also a legal appeal by the ministry, known as DETEC.

The government contended last week the ruling is flawed because it blurs lines of authority between it and the Swiss Federal Nuclear Safety Inspectorate, known as ENSI, which was spun off from the department in 2009 to make it an independent watchdog agency.

The two groups "administer their tasks independently of each other," the ministry said in a March 21 statement.

"The path marked out by the (court) leads in the opinion of DETEC to a mixing of duties by DETEC and the independent opinions of safety experts," it said, contending that interfering with the independence of the inspectorate would compromise its effectiveness and thus nuclear safety, the government said.

The court, however, ruled the issue of security was too important to be ENSI's sole responsibility.

BKW also indicated it would appeal the court's decision, saying it "raises fundamental questions that must be clarified by the federal court" and warning that "a premature shutdown" of the Muehleberg plant "would entail significant financial and technical implications."

"Some 3 terawatt-hours of electricity per year would need to be purchased on the market," the company warned. "Moreover, the values on the balance sheet on the shutdown date would need to be written down."

The Muehleberg plant, built in 1972, is one of five nuclear facilities in Switzerland and provides 5 percent of the country's energy needs. It was scheduled to be phased out after a three-month shutdown in 2011 revealed cracks in the reactor's core shroud, as well as other issues.

The court ruling also mentioned security concerns that include the inconclusive evaluation of the Muehleberg plant's vulnerability to earthquakes and its reliance on the nearby Aare River for cooling.

In light of the country's heavy reliance on nuclear power and the government's re-evaluation of its energy policy following the March 2011 Fukushima disaster in Japan, Switzerland has pledged to abandon nuclear power as an energy source by 2034.

The Muehleberg facility had been operating on a indefinite license, but the Swiss court's ruling -- pending appeals -- changed that and brought a celebratory reaction from anti-nuclear activists and officials in the neighboring Austrian state of Vorarlberg, who had filed a complaint against the plant.

"Should there be an accident, the people of Vorarlberg could be affected rapidly and seriously," Linz, Austria, lawyer Christian Hadeyer told the Swiss Broadcasting Corp.'s Swissinfo Web site.

Hadeyer, who is handling the case, said Vorarlberg residents are becoming more concerned about the plant, "especially since it has been learned that the construction is similar to that of the disaster reactor in Fukushima and we have seen with our own eyes what safety hazards there are."