Photo: The Canadian Press

Workers remove cladding from Whitebeam Court, in Manchester.

Britain's prime minister said Tuesday there must be a "major national investigation" of potentially flammable cladding on highrise towers, while a German city evacuated an 11-storey building because of safety concerns prompted by the fatal fire in London.

Theresa May's comments came hours before authorities in Wuppertal opted to evacuate an apartment block because of concerns over exterior panels similar to the ones used on London's Grenfell Tower, where at least 79 people perished.

Wuppertal officials said Tuesday the fire risk at the building had been reassessed following the June 14 fire, the dpa news agency reported.

Authorities in Britain, meanwhile, continued to test samples of building materials for flammability. All the samples submitted so far — coming from 95 buildings around England — have failed fire safety standards.

The national testing was ordered after flammable cladding was blamed for the rapid spread of the Grenfell Tower inferno.

The aluminum composite panels have been used for decades to help insulate buildings and improve their appearance, but the Grenfell tragedy has prompted hard questions about their regulation.

The government on Tuesday appointed an independent expert advisory panel to make recommendations on any immediate safety measures necessary.

Communities Secretary Sajid Javid said he wanted the public to be confident everything possible is being done as local officials scramble to prevent a similar tragedy.