local people, some of whom have never been allowed back to the contaminated towns.

The accident and its aftermath have resonance currently as new nuclear plants are being planned in Britain and other parts of Europe.

Nuclear power was heavily discredited for some time after Chernobyl because the accident pointed to the enormous dangers associated with it.

Ukraine and foreign contributors have already spent more than €750m trying to make safe the nuclear plant. The UK has so far provided €53.1m to help build the new shield and is under pressure to stump up a further €50m, although Ukrainian sources said no money had yet been promised.

With the 25th anniversary approaching, the European commission is encouraging governments to make public new cash commitments in advance of a "pledging" conference scheduled forone week before the April anniversary.

The European Bank for Reconstruction and Development, which has been overseeing the spending of the money at Chernobyl, admitted squeezing out more money at this time was a "big challenge".

Vince Novak, a director of the nuclear safety department of the EBRD in London, said the design life of the temporary shield thrown up by the-then Soviet Union in the immediate aftermath of the accident in 1986 "runs out" in 2016.

A new moveable barrier would be one of the world's biggest engineering feats due to its size and innovative features. The work will be done by a consortium involving Bechtel, the US firm which has worked on the London Underground and the Channel tunnel.

The current shield has been propped up by a series of