European Commission President Ursula von der Leyen on Thursday announced 10 billion euros (US$11 billion) in funds for member nations reeling from "heartbreaking" devastation after the floods caused by Storm Boris.

The death toll from the storm which struck central and eastern Europe last week rose to 24 on Wednesday and some areas are still under threat from rising waters.

Von der Leyen spoke in the Polish city of Wroclaw alongside the leaders of four countries from the flood-hit region.

"It was for me on the one hand heartbreaking to see the destruction and the devastation through the floods," she told reporters.

"But I must also say it was on the other hand heartwarming to see the enormous solidarity between the people in your countries," she added.

Von der Leyen said the European Union had two sources – cohesion funds and the solidarity fund – that it could use to "help with funding to repair and reconstruct" the damage.

"At first sight 10 billion euros are possible to mobilise from the cohesion funds for the countries that are affected. This is an emergency reaction now," she added.

Cohesion funds usually require co-financing from the member states but in this case von der Leyen said it would be "100 percent European money, no co-financing."

"These are extraordinary times and extraordinary times need extraordinary measures."

Strong wind and heavy rains struck the region last week, killing five people in Austria, seven in Poland, seven in Romania and five in the Czech Republic.

In some places, the water "literally destroyed everything. The landscape is like that after a war, rather than a flood," Polish Infrastructure Minister Dariusz Klimczak told reporters on Thursday.

The EU chief met with Polish Prime Minister Donald Tusk, his Czech counterpart Petr Fiala, Slovakia's Robert Fico, and Austrian Chancellor Karl Nehammer in Wroclaw, a historic city of 670,000 people in southwest Poland.

Struck by devastating floods in 1997, residents of Wroclaw had become increasingly concerned as the waters rose.

They reached their peak early on Thursday.

While the water level is lower than it was in 1997, dams could be at risk if the high water lasts for several days.

On Thursday, Tusk warned "against an atmosphere of unjustified euphoria and relief... that the worst is behind us."

But Wroclaw pensioner Ewa Powazka, 70, was optimistic.

"There are sandbags everywhere, something we didn't have in 1997. This time, the city began to prepare a few days ago," she said.

"I hope it won't get flooded."

Hungarian Prime Minister Viktor Orban was not present at the meeting as he cancelled all his international engagements this week because of the storm – even though his country has for now not been badly affected.

Romania's prime minister was also absent because of a defence meeting.

In Poland, several towns and villages have been devastated by the flood waters which have demolished houses, brought down bridges and heavily damaged road and rail infrastructure.

In some areas, residents still lack drinking water and electricity.

Grassroots funding initiatives have been organised across the country as local authorities begin to assess damage which could run into the hundreds of millions.

The Polish government says it has unblocked 470 million euros of direct aid to people and localities affected by the floods.

Austria has said its disaster relief fund will be increased to one billion euros to help flood victims.

The heavy rain pounded the Czech Republic on Friday and Saturday and raised river levels mainly in the north and northeast of the EU member.

The flooding there – which tore down houses, disrupted road and railway traffic and caused power outages – has since receded, revealing extensive damage. (AFP)