"It is a very worrying situation," said Jose Amarelinho, deputy mayor of Aljezur, a riverside town near the villages in the hills of southern Portugal.

Amarelinho said a line of flames more than five kilometres (three miles) wide was advancing on the villages. It was being fought back by 300 firefighters, backed by six water-dropping aircraft.

Rescue workers said they had escorted some 200 residents from the white-walled villages of Cerca, Moinho do Bispo, Marria Serrao and Monte Velho as the danger approached.

On Sunday emergency crews had evacuated about 300 people from the Algarve village of Marmalete after the fire veered towards it. The flames destroyed several houses on the outskirts of the village before residents were allowed to return home.

Until Saturday the Algarve, which receives the bulk of Portugal's summer visitors, had escaped damage from the fires that have been sweeping through the country since the heatwave began at the end of July.

The blaze currently raging in the Algarve is some 25 kilometres from the beach resorts where most tourists stay.

Firefighters said that persistent high temperatures and a strong easterly wind with gusts of up to 25 kilometres an hour were spreading the flames.

"The wind is frequently changing directions, which is complicating things," the duty officer at the National Rescue Operation Centre, Antonio Vieira, told TSF radio.

He said two more water-dropping helicopters and 50 more firefighters were on their way to the blaze.

Elderly people evacuated on Monday were given shelter in the fire department's headquarters in Aljezur, some 250 kilometres (120 miles) south of Lisbon.

"I left everything I have behind -- all my livestock, my home. I'm very scared," one of the evacuated villagers, Maria Francisca, told private radio

Portugal's weather office said on Monday the heatwave, which began on July 29, has lasted longer than any other bout of hot weather on its record books.

Temperatures soared above 40 degrees Celsius (104 degrees Fahrenheit) in much of central and southern Portugal during the day and were expected to remain high throughout the week.

Fires fanned by the scorching heat and strong winds have destroyed vast swathes of woodland in Portugal.

The forestry service estimated last Friday that more than 200,000 hectares (494,000 acres) of trees had gone up in flames this year, most of it since July. And forestry experts who studied satellite images of the fire damage told daily newspaper Publico on Sunday the total area burnt was likely to be at least 300,000 hectares.

Fifteen people have died in the blazes, which have destroyed dozens of homes, 2,000 kilometres of power lines and hundreds of telephone posts, causing damage of nearly one billion euros (1.1 billion dollars).

The authorities suspect that 30 percent of the fires which have raged over the past two weeks were started deliberately.

Police have arrested more than 50 people so far this year for allegedly starting fires, most of them in the past fortnight.

On Sunday they detained an 18-year-old shepherd, who they suspect deliberately started the fire in the Algarve.

On Monday a further four people were arrested in Guarda, northeastern Portugal, as they tried to start another fire, Lusa news agency reported.

TERRA.WIRE