Frank said homes and buildings within a 1.5-kilometre radius of the site were to be cleared by 0600 GMT, and residents will likely need to stay away until 1800 GMT.

"We must have this area completely cleared by 8am," Frank said.

The Westend district is home to many of Frankfurt’s top bankers, including European Central Bank chief Mario Draghi, who is known however to spend his weekends away from the German city.

Two major hospitals are also within the evacuation zone, including one with a big ward of newborns. Staff at the affected hospitals began transferring patients and infants to other medical centres beginning Saturday.