Germany wildfires: Hundreds flee as blaze threatens to detonate unexploded Second World War ammunition buried in forest

More than 500 people forced to leave their homes as a result of the blaze

Firefighters battle a wildfire near the village Klausdorf, about 53 miles south of Berlin (AP)

Efforts to tackle a wildfire spreading near Berlin have been complicated by old ammunition from the Second World War that is still buried in the forests around the German capital and could explode in the fire.

People from three villages have been forced to leave as the blaze, which is now the size of 500 football pitches, continues to spread.

"The ammunition is very dangerous, because one cannot step on the ground and therefore one cannot get close to the fire" to extinguish it, Brandenburg Governor Dietmar Woidke said.

More than 500 people had to leave their homes as a result of the fire in the Treuenbrietzen region, some 50 kilometres (30 miles) outside of Berlin.

"The fire continues to be a big threat," Mr Woidke said. "But we will do everything to protect people's property."

Local lawmaker Christian Stein said there had already been several detonations due to the ammunition, and that firefighters were not allowed to enter some areas.

Instead, the authorities were trying to douse the flames in those areas with firefighting helicopters and water cannons.

The fire started on Thursday afternoon and spread quickly through the dry pine forests. By the evening, the authorities had evacuated the villages of Frohnsdorf, Klausdorf and Tiefenbrunnen.

Overnight, winds blew the smoke to Berlin, where people in some neighbourhoods were asked to keep their windows closed.

Berlin emergency services received calls from concerned Berliners who were woken by the strong smell of smoke.

More than 600 firefighters and soldiers have been brought in to battle the wildfire. They are trying to cut trees to make long swaths in the forests to prevent the fire from spreading further.

Several roads were closed and local train operators stopped their service in the area close to the fire.

Germany has seen a long, hot summer with almost no rain, and large parts of the country are on high alert regarding possible wildfires.

Agencies contributed to this report