The German city of Wuppertal is to evacuate an 11-storey building over fears about exterior insulation similar to London's Grenfell Tower, according to reports.

Some 80 people were to be removed from the building after it was found to contain flammable materials.

However, a fire official told Reuters a separate report he could not confirm a story in the Wuppertaler Rundschau newspaper that the building was found to have the same exterior cladding involved in the fire that killed at least 79 people in London earlier this month.

"That would be speculative," the official said. "What we can say is that the building is being evacuated for fire safety reasons and flammable material was found."

It was unclear if the material was found as a result of an inspection ordered after the London fire or a renovation. City officials were not immediately available to comment.

Fire and city officials were moving residents to other living quarters, the spokesman said.

The fire in London has raised concerns about the cladding used on the facades of buildings, mainly for insulation or to improve their appearance.

Prime Minister Theresa May called on Tuesday for a national investigation into the cladding after all those checked after the London fire failed safety tests.