Chancellor Angela Merkel said on Sunday that she was horrified by the "surreal" devastation in the flood-ravaged region of Germany, as the toll in western Europe reached at least 184 people dead with dozens still missing.

Wearing hiking boots and offering pandemic-safe fist bumps to rescue workers, the veteran leader walked through the village of Schuld in Rhineland-Palatinate state, one of the two hardest-hit regions in western Germany.

Merkel, who is retiring from politics after September's elections, listened to the accounts of residents where the swollen Ahr River swept away houses and left debris piled high in the streets.

"It is a surreal, eerie situation," a visibly shaken Merkel told reporters, as she pledged quick aid to rebuild.

"It is shocking -- I can almost say that the German language doesn't have words for the destruction that's been wreaked."

At least 157 people have died since Wednesday in Germany's worst flooding in living memory, police said.

In Rhineland-Palatinate state alone, authorities reported 110 dead and 670 injured.

At least 27 people have lost their lives in neighbouring Belgium.

Rescue crews were sifting through rubble to find victims and survivors, often in dangerous conditions. Police deployed speedboats and divers to recover bodies swept away in the torrents.

Historic heavy rainfall also battered Switzerland, Luxembourg and The Netherlands.

As the waters began to recede in Rhineland-Palatinate and neighbouring North-Rhine Westphalia (NRW), concern shifted south to Germany's Upper Bavaria region, where torrential rains inundated basements and led rivers and creeks late Saturday to burst their banks.

One person died in Berchtesgadener Land, a spokeswoman for the Bavarian district told AFP.

In the eastern state of Saxony, authorities reported a "significant risk situation" in several villages.

In Austria, emergency workers in the Salzburg and Tyrol regions were on high alert for flooding. The scenic town of Hallein suffered severe damage after its streets were submerged.

Pope Francis expressed his "nearness" to the people of the stricken regions.

"May the Lord welcome the deceased and comfort their loved ones, may he sustain the efforts of everyone who are helping those who have suffered serious damage," he said on Sunday.

'Sorry' for laughing

German Finance Minister Olaf Scholz pledged more than 300 million euros ($354 million) in emergency aid for people who lost homes and businesses, with the cabinet to approve a much larger reconstruction package on Wednesday.

The disaster has increasingly taken on political overtones in Germany, which heads to the polls on September 26 for a general election that will mark the end of Merkel's 16 years in power.

With experts saying climate change is making extreme weather events more likely, Merkel said the world "must hurry" in the fight against global warming.

"We have to be faster in the fight against climate change."

Armin Laschet, the premier of hard-hit North-Rhine Westphalia (NRW) state and frontrunner in the race, has said efforts to tackle global warming should be "speeded up".

But Laschet scored an own goal Saturday when he was filmed laughing in the devastated town of Erftstadt in NRW, where a landslide was triggered by the floods.

In the footage, Laschet could be seen chatting and joking in the background as President Frank-Walter Steinmeier gave a statement expressing his sympathies to grieving families.

"Laschet laughs while the country cries," wrote the top-selling Bild daily.

Laschet later apologised on Twitter for the "inappropriate" moment.

Divers, armoured vehicles

The scale of the flood impact was gradually becoming clear in Germany, with damaged buildings being assessed, some of which will have to be demolished, and efforts under way to restore gas, electricity and telephone services.

In some areas, soldiers used armoured vehicles to clear the debris clogging streets.

Local authorities in NRW and Rhineland-Palatinate said dozens of people remain unaccounted for across both states, possibly due to communication disruptions.

Across the border in Belgium, the death toll rose to 27 with many people still missing.

European Commission President Ursula von der Leyen and Prime Minister Alexander de Croo visited the flooded areas of Rochefort and Pepinster together on Saturday.

"Europe is with you," von der Leyen tweeted afterwards. "We are with you in mourning and we will be with you in rebuilding.”