Hungary on Thursday moved to make safe a disused Budapest chemical plant that environmentalist group Greenpeace said was in a "catastrophic" state.

Over 2,000 tonnes of dangerous toxic waste were found recently at the Budapest Chemical Works -- which closed in 2008 -- in an industrial zone bordering a densely populated neighbourhood in the Hungarian capital.

The inflammable and toxic materials stored in open air in often leaking barrels were spotted by the news website 444.hu earlier this month.

"Negative" test results have forced the immediate removal of the waste, Richard Tarnai, a government official, told reporters at the site Thursday.

Tarnai said removal of 1,000 barrels of the most dangerous waste could begin at once while the rest of the estimated 2,800 tonnes of material would be removed "within months".

The move was welcomed by Greenpeace which had described the situation as "catastrophic" and called for swift action.

"We hope removing the barrels is not the end of the story, some of the waste has leaked into the ground, potentially exposing the local population to risk," Gergely Simon, a chemicals expert for Greenpeace, told AFP.

Waste removal and site clean-up would cost an estimated 1.2 billion forints (around 3.9 million euros), according to government estimates.