Belgian wildfire doubles in size on third day tearing through nature reserve

A wildfire described as the largest in Belgium's recent history has more than doubled in size in 24 hours, local officials said on Sunday.

Hundreds of firefighters are spending a third day beating back flames tearing through Hautes Fagnes - the country's largest nature reserve - prompting the evacuation of two nearby villages.

Local farmers hauled water tankers towards the park near Belgium's eastern border with Germany, backed by water-bombing aircraft and helicopters sent from Sweden and the Netherlands.

The blaze is one of several wildfires reported across Europe this weekend, with at least two killed in forest fires on a Greek island off the coast of Athens on Sunday.

Belgian officials have warned that high heat and the park's terrain - which consists of bog-like territory, moorland and forests - have hampered efforts to extinguish the fire.

It spread from 80 hectares (200 acres) on Friday to 850 hectares on Saturday morning - before consuming 3,000 hectares by early Sunday, AFP news agency reported citing local officials.

Belgian Interior Minister Bernard Quintin said two of its fronts - heading towards Jalhay and Monschau - had been brought under control.

But the blaze continued to advance on Sunday, with its active front reported to be a kilometre long.

Authorities earlier said the conditions remained challenging and that they were relying heavily on aerial assistance to tame the flames, though no homes have been affected.

Two water-bombing aircraft arrived from Sweden on Sunday afternoon to back up four helicopters - two Belgian and two Dutch - already on site.

Nicolas Yernaux, spokesman for the regional authorities in Wallonia, had said on Saturday that the fire was the country's "largest in recent history".

Firefighters had "allowed parts of the heathland to burn because the area is very difficult to access", he added.

Rescue teams have been unable to access the area where fire broke out, meaning its cause remains unknown.

Forest fires have also been reported in Croatia, Spain and Serbia since Friday, after a summer of extreme heat that has seen swathes of land across Europe either going up in flames or being scorched brown .