The European Union and the UN's food agency announced an agreement on Thursday to manage vast stocks of obsolete pesticides in the former Soviet Union, warning they had become a "serious threat".

The EU and the Food and Agriculture Organisation (FAO) will spend seven million euros ($9.1 million) over the next four years to help contain the risks in 12 countries in the region, spanning Russia, the Caucasus and Central Asia.

"It is estimated that around 200,000 tons of obsolete pesticides, nearly half the world's stockpiles, can be found" in the region, FAO said.

"Kept in tens of thousands of unprotected sites, they pose a serious threat to the health of the people around them and to the environment," it said.

The 12 countries to be helped are: Armenia, Azerbaijan, Belarus, Georgia, Kazakhstan, Kyrgyzstan, Moldova, Russia, Tajikistan, Turkmenistan, Ukraine and Uzbekistan -- all the former Soviet republics except for the Baltic states.

"Pesticides may be an important input for farming, but they need to be used responsibly while protecting human health and the environment from their adverse effects," FAO chief Jose Graziano da Silva said.

The project will include disposal of stockpiles, as well as moves to promote legal reforms, new registration procedures, a regional training centre and the promotion of natural alternatives to hazardous pesticides.