The United States, Israel, Turkey, Slovenia, Austria, Luxembourg and Croatia have offered aid to Balkan states suffering their worst floods in 120 years.

Croatia has some flooding itself in the east but the town of Obrenovac in Serbia is the hardest-hit.

It's likely the region's entire population of 25,000 will be evacuated.

Bosnia's also appealing for international help to handle the floods.

At least 20 people are known to have died, nearly all in Bosnia.

In eastern Croatia about 1, 000 troops have been deployed to help with relief effort in flooded areas.

Forecasters are warning of surges of high water expected to reach the Sava and Danube rivers threaten thousands more properties and roads.

What's being described as three months of rainfall in just three days also threatens further dangers as many hillsides have become unstable.