A police spokesman in Gudensberg, in north Hesse, confirmed the fire on Monday night in the building where Polish and Bulgarian workers were living. "We do not have any information," police said when asked about possible reasons for the arson.

A speaker for the fire brigade said the house was completely engulfed in flames, from the ground floor to the roof. Neighboring buildings had been evacuated and police had cordoned off the area. Police said, except for a gable wall, most of the building had collapsed into the neighboring house. Fire investigators were looking into possible reasons for the arson in the meantime.

Initial reports said 40 people were injured, but the number could not be confirmed. 48 people were registered as living in the building, police told reporters. Gudensberg is in northern Hesse and is 20 kilometers (12.5 miles) away from the city of Kassel. The workers' house was located in the town center, which has about 9,000 residents.

Meanwhile, another planned refugee accommodation was destroyed in eastern Germany on Monday. Vandals flooded a refugee shelter in Thuringia's Frauenwald, destroying 17 flats in a block. The local administration had rented the building from a private owner. Police have still not made any arrests.

Five refugee shelters have been set alight in the German state in the last few weeks following the arrival of thousands of refugees fleeing war and poverty in the Middle East and Africa.

mg/rc (AFP, dpa)