Sunday 27 February 2011 12.53 EST
First published on Sunday 27 February 2011 12.53 EST

Britain is coming under increasing pressure to provide Ukraine with an extra €50m (£43m) to construct a new contamination shield over the top of the stricken Chernobyl nuclear plant before the old one collapses.

Officials from the European commission said governments around the world were being urged to find €750m to help build a more sophisticated roof over the burnt-out reactor and storage for 200 tonnes of highly radioactive fuel.

Jean-Paul Joulia, from the commission's nuclear safety unit, admitted the cost of just this aspect of the Chernobyl clean-up was running at €1.5bn – double the original estimate – partly due to "some delays" to some projects.

But he said he was confident that foreign governments would stumpup the money needed for the shield, even in today's financially difficult climate. "I am optimistic the international community is committed to this. It is important for a number of reasons," he said.

The disaster at Chernobyl, on 26 April 1986, is recognised as the world's worst nuclear accident. One of the power station's reactors exploded and the subsequent fire spewed a radioactive cloud across Europe.

The accident claimed the lives directly of at least 50 people, mainly fire crews and nuclear workers who tried to fight the fire on the fateful night.

Radioactive fallout is believed to have caused many other deaths from thyroid cancer and related illnesses, with an eventual death toll estimated at anywhere between 4,000 and 200,000.

The disaster also triggered the relocation of tens of thousands of