Yanukovych spoke on Tuesday at a nuclear safety conference in Seoul, where he also pledged to share Ukraine's experience after Chernobyl with Japan, which has to deal with the consequences of its own nuclear disaster after a series of failures at the Fukushima power plant last year.

The Chernobyl sarcophagus will cost 935 million euro ($1.2 billion) to build. Most of the money was raised through a donation drive among the world’s governments held last year, with Ukraine only contributing 6 percent of the sum.

Construction of the confinement chamber, a metal facility 105 meters tall and 260 meters long that will cover the reactor, is to be finished by 2015, Ukrainian officials said earlier.

The destroyed reactor was covered by a concrete confinement chamber months after the disaster in 1986 but the facility has since decayed and is threatening to leak radiation.