BERLIN, June 25 (Xinhua) -- A speed limit was imposed on two German autobahns as temperatures soared, spokesperson for the Ministry of Regional Development and Transport in the federal state of Saxony-Anhalt announced on Tuesday.

Several already damaged sections of the Autobahn 9 and 38 were affected, "where speed limits will apply until further notice," the head of state road construction authority for Saxony-Anhalt, Uwe Langkammer, told the German Press Agency (dpa).

The speed limits on two stretches of the German highway were introduced amid concerns over the danger of so-called "blow-ups" in the heat.

"Long periods of high temperatures can cause the concrete to expand, causing the individual roadway slabs to rise slightly," said Andreas Tempelhof, spokesperson for Saxony-Anhalt's transport ministry.

This caused the road surface of the Autobahns to bulge or break, which "could pose a safety risk to road users at high speeds," Tempelhof noted.

The German weather service (DWD) is expecting temperatures of up to 40 degrees Celsius this week that will most likely break the previous June temperature record from 1947 of 38.5 degrees.

The warm and dry weather was also increasing the risk of forest fires in Germany and the DWD reported the highest forest fire hazard level of five in some federal states.

On Tuesday night, a forest fire expanded to more than 100 hectares in the Lieberoser Heide, a former military training area 90 km southeast of Berlin, according to a police spokesperson.

The same area had already experienced a fire spanning 400 hectares in July 2018, and almost 1,000 square meters burned at the beginning of June this year.

As the area is a former military training area, there was a risk that ammunition could still be buried in the ground and so fires could only be fought from the air, according to local German police.

The German Federal Police would therefore be supporting the extinguishing work in the former military training area with two helicopters.