The environmental group published findings of a field investigation ahead of a Ukraine-hosted international conference on Chernobyl on April 19.

The meeting has taken on added significance since the nuclear crisis in Japan.

Ukraine is seeking 600 million euros ($840 million) in extra funding to build a massive new shell over a reactor at the Chernobyl plant which blew up in 1986, spewing radioactive debris across neighboring Belarus and other parts of Europe.

The investigation in three parts of Ukraine earlier this month focused on contamination of locally-produced food by caesium-137, a radionuclide carried around the region by wind at the time.

The findings showed varying degrees of contamination in food such as milk and milk products, mushrooms, berries and root vegetables like beetroot and potatoes, staples of the rural diet in Ukraine.

In many cases the presence of cs-137 was well above acceptable levels for children and adults.

Cs-137 "represents a long-term threat to the public's health particularly for people who consume this food on a daily basis," Greenpeace scientist Iryna Labunska told a briefing.

The Greenpeace report was especially critical of the Ukrainian government for suspending regular monitoring of food contamination from Chernobyl two years ago.

"It is absolutely premature to end this monitoring programme by the government because we still have to know the situation to be able to help people deal with these problems," Labunska said.

"There is an urgent need for thorough, scientifically based evaluation of radionuclide contamination of agricultural land, and adequate remedial treatment of all lands proposed for a return to agricultural use," Greenpeace said in a statement.

The investigation was carried out beyond a 60-km (38-mile) exclusion zone around the Chernobyl plant that has been deemed unsuitable for living.

The new cover for Chernobyl's stricken no. 4 reactor will replace a hastily-built 1986 concrete tomb which has since begun to leak.

(Reporting and Writing by Richard Balmforth; Editing by David Cowell)