Portugal appealed for further international aid Monday to tackle forest fires raging in the country's north and centre, with 30-metre flames towering over villagers in some areas.

The fires continued unabated after claiming the life of a female firefighter last week, despite French and Spanish jets dropping water on the affected regions.

A week without a break was taking its toll on firefighters in Tondela, central Portugal. "We sometimes forget to eat," fire chief Carlos Dias told the Jornal de Noticias newspaper.

"I sleep in half-hour bursts in the car. It's not very comfortable but it's better than nothing," added his colleague.

Miguel Cruz, spokesman for the Civil Protection Authority, said the fires were likely to subside from Wednesday as temperatures fell, but called on France to extend its help.

"We had... an average of 250 to 300 fires a day in inaccessible places, often simultaneously, with a low rate of humidity and strong winds," Cruz said.

In the town of Feitalinho, central Portugal, 400 firefighters and two French planes tackled a blaze Monday, while 500 more took on fires in the north and centre of Portugal.

Two Spanish bombardiers deployed to help put out the fires returned home at the end of last week, and were replaced by the French planes.