High temperatures and strong winds were making it difficult to bring the blaze under control, firefighters said. The fire began on Sunday afternoon in a mountainous area located some 260 kilometres (160 miles) north of Lisbon near the town of Silvares.

"The wind blew hard all night, in various directions, and we were not able to put the fire out," fire brigade commander Antonio Antunes told state radio Antena 1.

The firefighters, who came from across the country, were equipped with four helicopters and six airplanes, including two which arrived from neighbouring Spain following a request for help from Portuguese authorities.

Firefighters said one of the two fronts of the fire was out of control but no homes were in danger.

Most of the 70,000 residents of the nearby city of Castelo Branco were without electricity and telephone service, the Lusa news agency reported.

A local official of electrical company EDP told the agency technicians were trying to determione if the fire was behind the power outage.

Officials told private television private television SIC Noticias they suspected the fire had been deliberately set.

Forests cover roughly one-third of Portugal and forestry accounts for 11 percent of the nation's exports, but each summer thousands of trees are destroyed by fires.

There were some 25,000 forest or brush fires last year in Portugal which burned almost 120,000 hectares (296,400 acres) of land, according to forest service figures.

Portugal lost 16 percent of its forest land in fires during the 1990s. During this same period Greece and Spain, which also experience long dry summers, lost six percent of their forests to flames while Italy and France lost just two percent.

Officials estimate that less than 10 percent of all fires are caused by natural causes. Firefighters blame the vast majority of blazes on either negligence on the part of campers and farmers or arson.

Environmentalists argue a large number of fires could be avoided if the government did more to clear forests of overgrown brushes which can easily ignite.

TERRA.WIRE