MADRID (EFE Dow Jones)--A Spanish high court confirmed Thursday that the nuclear plant Santa Maria de Garona will be shut down as planned in 2013, rejecting a lawsuit filed by utilities Iberdrola SA (IBE.MC) and Endesa SA (ELE.MC) asking for a life extension and a monetary compensation.

The Audiencia Nacional court ruled in favor of the Spanish government decision to shut down the nuclear plant, arguing that the government is in charge of energy policy, according to the ruling published Thursday.

"[The decision] is sufficiently motivated and they're legitimate reasons of energy policy, so it is not arbitrary," said the ruling.

Garona, located in Burgos, northern Spain, is the smallest one in the country, with 460 MW of installed capacity. The plant is owned 50/50 by Spanish electricity giant Iberdrola and Endesa, a subsidiary of Italian energy group Enel SpA SA (ENEL.MI).

The ruling is important because it could set a precedent for the shutdown of other nuclear power plants. In July 2009, the government issued an order to close Garona in July 2013 against the opinion of the National Security Council, the nuclear sector regulator in Spain.

Garona fulfilled its useful life of 40 years in 2011. The government has said that it wants to promote renewable energies and that the plant is not essential to ensure the power supply.

Iberdrola and Endesa argued that the plant is in good condition and meets safety standards, so they asked for a life extension until 2019.

A spokesman for Nuclenor, the company that manages Garona, said its lawyers are already studying the ruling to decide to take legal action. The ruling may be appealed at Spain's Supreme Court.

-By Juan Montes, EFE Dow Jones; +34 91 395 81 36, juan.montes@dowjones.com