The death toll from disastrous flooding in western Europe has risen above 150 as rescue workers toiled to clear up the devastation and prevent further damage.

Police said more than 90 people are known to have died in western Germany's Ahrweiler county, in hard-hit Rhineland-Palatinate state.

Another 43 people were confirmed dead in neighbouring North Rhine-Westphalia, Germany's most populous state.

Belgian broadcaster RTBF reported that the death toll in Belgium rose to 24 on Saturday.

Waters are receding across many of the affected regions, but officials fear that more bodies might be found in cars and trucks that were swept away.

German President Frank-Walter Steinmeier plans to travel to Erftstadt, south west of Cologne, where a harrowing rescue effort unfolded on Friday after people were trapped when the ground gave way.

At least three houses and part of a mansion in the town's Blessem district collapsed.

The German military used armoured vehicles on Saturday to clear away cars and trucks overwhelmed by the floodwaters on a nearby road, some of which were still at least partly submerged.

Officials feared that some people didn't manage to escape in Erftstadt, but by Saturday morning no casualties had been confirmed.

In the Ahrweiler area, police warned people of a potential risk from downed power lines and urged curious visitors to stay away, as would-be sightseers were blocking some roads.

Many areas are still without electricity and telephone service which, combined with multiple counting in some cases, appears to have accounted for large numbers of missing people that authorities gave immediately after the floods hit on Wednesday and Thursday.

Around 700 people were evacuated from part of the German town of Wassenberg, on the Dutch border, after the breach of a dyke on the Rur river.

Train lines and roads remained blocked in many areas of eastern Belgium. The national railway service said traffic would start returning to normal on Monday.

European Commission president Ursula von der Leyen and Belgian Prime Minister Alexander De Croo were visiting flood-damaged towns on Saturday, according to state broadcaster RTBF.

Southern parts of the Netherlands have also been hit by heavy flooding, and volunteers worked through the night to shore up dykes and protect roads.

Thousands of residents of the southern towns of Bunde, Voulwames, Brommelen and Geulle were allowed to return home on Saturday morning after being evacuated on Thursday and Friday.

Caretaker Prime Minister Mark Rutte, who visited the region on Friday, said the region faced "three disasters".

"First, there was corona, now these floods, and soon people will have to work on clean-up and recovery," he said.

"It is disaster after disaster after disaster. But we will not abandon Limburg," the southern province hit by the floods.

His government has declared the flooding a state of emergency, opening up national funds for those affected.

In Switzerland, heavy rain caused several rivers and lakes to burst their banks, with authorities in the city of Lucerne closing several pedestrian bridges over the Reuss river.