MAYEN, July 16 (AFP) - Heavy rains and floods lashing western Europe have killed at least 59 people in Germany and nine in Belgium, and many more people are missing as rising waters caused several houses to collapse on Thursday (Jul 15).

In Germany, which is experiencing one of the worst weather disasters since World War II, desperate residents sought refuge on the roofs of their homes as rescue helicopters circled above.

Unusually heavy rains also inundated neighbouring Luxembourg, the Netherlands and Belgium.

On a visit to Washington, German Chancellor Angela Merkel said her "heart goes out" to the victims of the flooding.

"I fear that we will only see the full extent of the disaster in the coming days," she said, adding that the government is doing its "utmost to help (people) in their distress".

US President Joe Biden, speaking alongside Merkel at a joint news conference, offered his "sincere condolences and the condolences of the American people for the devastating loss of life and destruction".

Around 15,000 members of the German emergency services, police and army were on the ground in the worst-hit areas.

Pensioner Annemarie Mueller, 65, looking out at her flooded garden and garage from her balcony, said her town of Mayen had been completely unprepared for the destruction.

"Where did all this rain come from? It's crazy," she told AFP, recalling the floodwater crashing through her street during the night.

"It made such a loud noise and given how fast it came down, we thought it would break the door down."

North Rhine-Westphalia (NRW) premier Armin Laschet, who is running to succeed Merkel in September elections, cancelled a party meeting in Bavaria to survey the damage in his state, Germany's most populous.

"We will stand by the towns and people who've been affected," Laschet, clad in rubber boots, told reporters in the town of Hagen.

He called for "speeding up" global efforts to fight climate change, underlining the link between global warming and extreme weather.

Because a warmer atmosphere holds more water, climate change increases the risk and intensity of flooding from extreme rainfall.