BERLIN (AFP).- Fire broke out Wednesday at the central Berlin site where the German imperial family's palace is being reconstructed, injuring one and sending black smoke pouring into the sky.

The fire broke out outside the building in two tar kettles, causing a propane gas cylinder to explode before around 80 firefighters extinguished the blaze.

"Pictures of fire above the entrance to the palace sent shivers down all our spines," junior minister for culture Monika Gruetters said in a statement.

One worker was slightly hurt by smoke inhalation, firefighters said.

"Everything is under control again," the emergency responders posted on Twitter.

The Humboldt Forum, a museum slated to open in the rebuilt palace in autumn, said work on the building would not be slowed by Wednesday's upset.

Standing on the same site since the 15th century and home to Prussia's royal Hohenzollern family, the Stadtschloss was demolished by the communist East German government in 1950 after being damaged in World War II bombing.

Under construction since 2013, the new structure with reproduction facades and a modern interior is slated to open in the autumn as a cultural and research centre.

The Humboldt Forum will host items from Berlin's ethnological and Asian art museums, as well as from the scientific collections at the neighbouring Humboldt University and libraries.

Reconstruction of the palace has itself been controversial, as it meant tearing down the "Palace of the Republic" that stood on the same spot until 2008.

Housing the East German parliament and a leisure centre including a bowling alley until reunification in 1990, the building was dear to many citizens of the former communist state.

© Agence France-Presse