The Hague - Threats posed by global warming to large parts of the Dutch coastline and river plains are more serious than estimated and countermeasures requiring billions of euros are needed, an expert group warned Wednesday.

The findings were contained in a long-term study by the Delta Commission set up by the Dutch government under the leadership of Cees Veerman, a former agriculture minister.

Sea levels are rising even quicker than feared, Veerman said when he handed over the study to Prime Minister Jan Peter Balkenende.

The report said the Netherlands has to expect the sea level to rise between 65 and 130 centimetres by 2100 and by up to two metres by 2200.

To avert serious flooding in the country, one quarter of which lies below sea level, annual investments averaging 1.5 billion euros (2.2 billion dollars) will be needed, it said.

Measures should include improvements to the thousands of kilometres of dykes in use as well new barriers to prevent flooding by the sea and the large rivers Rhine and Meuse.

Future action should also include "intelligent water constructions" that take the natural environment into account. This "cooperation with the water" could be achieved by the preservation of mud flats and spillover areas of rivers, the report concluded. (dpa)