Parts of central and Eastern Europe paralysed by heavy snow could face further disruption and death from flooding as the spring thaw begins, the UN's disaster reduction agency warned on Tuesday.

Temperatures in Bulgaria and Romania are expected to rise to between eight and 10 degrees Celsius (46 and 50 degrees Fahrenheit) over the next 10 days, breaking up the ice along the Danube river.

"While thousands of people remain snowbound from Serbia to Bulgaria, there are warning signs that destructive floods will add to the loss of life and economic assets," said Margareta Wahlstroem, UN special representative for disaster risk reduction in a statement.

Places without adequate flood management infrastructure such as dams and dykes will be hit in particular, she added.

The recent cold snap and massive snowfall across parts of Europe has claimed more than 600 lives.

The extreme weather has seen whole communities cut off from transport, schools, hospitals and electricity.

"It's time now for the authorities in these countries, the Red Cross, the national platforms for disaster risk reduction and the civil protection authorities to make plans to make sure there is no loss of life when the floods do come," said Denis McClean, spokesman for the UN Office for Disaster Risk Reduction (UNISDR).

"But also to think how this disaster has exposed the current state of public infrastructure in these countries."

The European Commission set up the European Flood Alert System (EFAS) following the river Elbe and Danube floods in 2002.

The UNISDR said the forthcoming melt could put the system to its greatest test since then.