KIEV, January 24 (RIA Novosti) - The construction of a huge new protective cover for the Chernobyl reactor, the site of the world's worst nuclear disaster, will start this spring, Ukraine's emergencies ministry said on Thursday.

The plant's reactor No. 4, which exploded in 1986, has been protected by a concrete Soviet-designed "sarcophagus" since the disaster. The construction of a new shelter to cover the crumbling structure, now long overdue, has been repeatedly put off due to funding difficulties.

"I believe that in spring we'll start work to build a safe shelter and the construction of this facility will be completed in 2012," Ukrainian Emergencies Minister Volodymyr Shandra said.

In September 2007, Ukraine signed a contract with France's Novarka to build a shelter over the damaged Chernobyl reactor and also a deal to build a "dry storage" facility for spent nuclear fuel on the site of the plant with U.S. company Holtec International.

Vast areas, mainly in the three then Soviet republics of Ukraine, Belarus and Russia, were contaminated by the fallout of the 1986 explosion. More than 300,000 people were relocated after the accident. However 5 million people still live in areas of Belarus, Russia and Ukraine classified as "contaminated" with radioactive elements.

An 18-mile zone around the reactor remains largely deserted to this day.