LONDON -- Britain's prime minister said Tuesday there must be a "major national investigation" of potentially flammable cladding on high-rise towers, while a German city evacuated an 11-story 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.

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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.

Police secures a high-rise residential building from which the city of Wuppertal evacuated around 80 people after it was found to contain flammable materials, in Wuppertal, Germany, June 27, 2017. REUTERS/Leon Kuegeler

Police on Tuesday formally identified a 5-year-old boy as one of youngest victims of the disaster. Isaac Paulous died of inhaling fire fumes, Westminster Coroner's Court officer Eric Sword said Monday.

Isaac, who lived with his family on the apartment tower's 18th floor, perished as his family tried to escape the blaze. The child's body was found on the building's 13th floor and had to be identified through dental records.

"Isaac our beloved son was taken from us when he was only 5 years old," his family said in a statement released by police. "We will all miss our kind, energetic, generous little boy."

Coroner Fiona Wilcox said that 18 of the victims have so far been formally identified. Work on identifying the others is complex and ongoing, she said.

Meanwhile, Arconic says it is discontinuing global sales of one type of composite paneling for high-rise buildings. Arconic said in a statement Monday that Reynobond PE, a kind of cladding used in the apartment building, would no longer be sold for use in high-rises.

The company said that it believes "this is the right decision because of the inconsistency of building codes across the world and issues that have arisen in the wake of the Grenfell Tower tragedy regarding code compliance of cladding systems in the context of buildings' overall designs."

In a statement to CBS MoneyWatch, an Arconic spokesperson said last week that "one of our products, an aluminum composite material, was used as one component in the overall cladding system of the Tower. We will fully support the authorities as they investigate this tragedy."