KIEV, Aug. 6 - The European Bank of Reconstruction and Development has pledged $507 million to help Ukraine build a new shelter for the Chernobyl reactor, the site of the world's worst nuclear accident, The Associated Press reported Monday.

Chernobyl's reactor No. 4 exploded and burned on April 26, 1986, spewing radiation over a large swath of the former Soviet Union and much of northern Europe. An area roughly half the size of Italy was contaminated, forcing the resettlement of hundreds of thousands of people and ruining some of Europe's most fertile farmland.

A protective "sarcophagus" that was hastily erected over the reactor is now crumbling, and a $1.2 billion project to replace it remains on the drawing board. Ukraine has repeatedly asked for money from the European Union and other Western sources to fund a new shelter.

More than $600 million has already been pledged by 28 donor governments.

Lyudmila Shcherban, an Emergency Situations Ministry spokesman, said the money will go toward the new shelter as well as freezing the reactor permanently to prevent further ecological damage, AP reported.

Thirty-one people died within the first two months from illnesses caused by radioactivity, but there is heated debate over the subsequent toll. A report from the U.N. health agency last year estimated that about 9,300 people will die from cancers caused by Chernobyl's radiation. Some groups, such as Greenpeace, insist the toll could be 10 times higher.

The EBRD is the largest financial investor in Ukraine, having invested in 77 projects in sectors ranging from banking to infrastructure to small and medium-sized enterprises.(ap/ez)