Wildfires which have blazed along a stretch of Portugal's Algarve for a week died down on Thursday, but fears remained that winds could reignite the flames.

"It's calmer and we do not have active flames any more, and that gives us some peace of mind," said Rui Andre, the mayor of Monchique close to where the fire broke out last Friday.

Hundreds of firefighters have been battling to control the blaze that has menaced the popular tourist region in southern Portugal for a week as sweltering temperatures and strong winds fanned the ferocious fires.

Dozens of people were injured and a blackened trail of seared forest, charred homes and incinerated cars was left in the wake of the wildfires.

Aircraft scooped water from the sea to drop onto the fires earlier Thursday, as firefighters continued to douse the flames, which have consumed some 27,000 hectares (67,000 acres) of forest in the region -- one of Europe's top tourism destinations.

Weaker winds, with speeds of less than 15 kilometres (nine miles) per hour, combined with lower temperatures and higher air humidity levels were helping firefighters to get the upper hand against the wildfires although the "risk of reactivation" of the flames during the day on Friday remained high, said national civil protection agency spokeswoman Patricia Gaspar.

"It is a very different scenario," she told a news conference.

Maximum daytime temperatures in the region have dropped from around 35 degrees Celsius (95 degrees Fahrenheit) at the weekend to 24-26 degrees Celsius.

- 'Very nerve-wracking' -

Aircraft scooped water from the sea to drop onto the creeping blaze Thursday, as firefighters continued their struggle to douse the flames, which have already consumed some 21,000 hectares (52,000 acres) of forest in the region / © AFP

The fires have left 39 people injured, one seriously, with 21 of those hurt firefighters, according to Gaspar.

On Thursday more than a thousand firefighters and soldiers were tackling the blazes in the affected zone, which is planted with pines and highly-flammable eucalyptus trees and scored by difficult to reach valleys and ravines.

Fire crews and police conducted an urgent evacuation overnight of homes around the historic town of Silves.

Images broadcast on Portuguese TV showed a man wearing a face mask running with a dog in his arms as police knocked on doors in the background to urge people to leave.

Gerry Atkins, an 80-year-old Briton who lives in a house in the countryside some 12 kilometres from Silves, packed his car with some clothes, his passport and other important documents in case he also needed to flee.

"It was very frightening because we had police cars flying up past up our little road. We kept our eye on the fire. It is all very nerve-wracking," he told AFP.

The slight respite Thursday afternoon enabled local people to leave the schools, gymnasiums and reception centres where they had taken refuge and venture back to their homes.

- Endangered lynx evacuated -

A Europe-wide heatwave sent the mercury above 45 degrees Celsius (113 Fahrenheit) in some areas of Portugal at the weekend, intensifying wildfires that began last Friday.

Aircraft have scooped water from swimming pools and the sea to drop onto the creeping blaze, as firefighters struggle to douse the flames / © AFP

Hundreds of residents and tourists have been evacuated from around Monchique, a popular spa town of 6,000 people some 160 kilometres from Lisbon, where the blazes began.

Prime Minister Antonio Costa on Wednesday warned the blaze would continue to rage "during the coming days".

The difficulty in bringing the fires under control has raised doubt about the effectiveness of measures taken by the Portuguese authorities to avoid a repetition of fires that killed at least 114 people last year.

Firefighters have criticised the lack of coordination, while Costa has drawn flak on social media for remaining on holiday as the flames raged.

The blazes have left 36 people injured, one seriously, with 19 of those hurt firefighters / © AFP

The spreading blaze has even necessitated the evacuation of some 29 endangered Iberian lynx to Spain from the national reproductive centre, according to a statement from the country's conservation institute.

In Spain, where more than 700 firefighters continued to battle wildfires in the province of Valencia, authorities said they were hopeful of bringing an end to the threat.

The blaze "has been stabilised", said Valencia emergency services chief Jose Maria Angel, adding the hope of an improving situation over the course of the day.

Authorities have established that the fires were started by lightning during an electric storm on Monday.

A sizzling heatwave across Spain has left 10 people dead in a week.