International donors agreed to pay an extra 180 million euros ($201 million) to fund a new cover for the disused Chernobyl nuclear power plant at a conference in London on Wednesday.

"Chernobyl pledging event raises 180 million euros to close funding gap," the European Bank for Reconstruction and Development (EBRD), which is managing the talks, said in a statement.

The main share -- 165 million euros -- was pledged by members of the Group of Seven (G7) leading industrialised nations and the European Commission.

The money comes on top of 350 million euros promised by the EBRD in November and the bank said the funding gap for the new project had now been reduced to 85 million euros.

Work is ongoing on a new 20,000-tonne steel cover at Ukraine's Chernobyl plant -- scene of the world's worst civil nuclear disaster in 1986 -- a project estimated to cost 2.15 billion euros.

The structure will contain technology that will act beneath the cover to decontaminate the area once the steel layer is in place.

Officials say the new cover will last for 100 years.

The work is being done by Novarka, a joint venture by French companies Vinci and Bouygues.

The project had been scheduled for completion by the end of this year but the EBRD said last year that technical problems would delay it until late 2017.

The explosion of Chernobyl reactor number four on April 26, 1986, spewed poisonous radiation over large parts of Europe, particularly Ukraine, Belarus and Russia.

At the site of the plant itself, around 100 kilometres (60 miles) from Kiev, Ukraine's President Petro Poroshenko laid a wreath at a monument to the victims on the anniversary on Sunday.

pn/dt/jwp/pvh

Vinci

Bouygues