* Fipronil use restricted due to link with falling bee numbers
* Decision follows earlier EU ban on widely used pesticides
* Scientists divided over pesticides' role in bee deaths (Recasts lead, adds BASF reaction, details, background)
By Charlie Dunmore
BRUSSELS, July 16 (Reuters) - The European Union added a pesticide made by German chemical firm BASF to its blacklist of substances suspected of playing a role in declining bee populations.
Member governments banned the use of agricultural insecticide fipronil to treat maize and sunflower seeds, the European Commission said.
The restrictions take effect from Dec. 31 but seeds which have already been treated can be sown until the end of February 2014.
The ban follows similar EU curbs imposed in April on three of the world's most widely used pesticides, known as neonicotinoids, and reflects growing concern in Europe over a recent plunge in the population of honeybees critical to crop pollination and production.
A scientific assessment from the EU's food safety watchdog EFSA said in May that fipronil posed an "acute risk to honeybees when used as a seed treatment for maize".
Fipronil, mainly sold under the Regent brand name in Europe, may still be used on seeds sown in greenhouses, or leeks, shallots, onions and other vegetables that are harvested before they flower, posing a low risk to foraging bees.
BASF said in a statement it disagreed with the decision and remained convinced the decline in bee numbers was due to other factors.
"We will support the European Commission in the development of extensive measures that can benefit bees while securing food production in Europe. We do not believe that the planned restriction of fipronil uses will accomplish that," said Juergen Oldeweme of BASF's Crop Protection division.
In a vote on Tuesday in the EU's standing committee on the food chain and animal health (SCFCAH), the ban was backed by 23 member states, with three abstentions. Spain and Romania - where fipronil is used commercially - opposed the measures.
Scientists are divided on the part played by pesticides such as neonicotinoids in the sharp decline in bee numbers in Europe in recent years - a phenomenon known as "colony collapse disorder".
The European Commission says pesticides are one of several factors which may be responsible, along with parasites, diseases and shrinking habitats.
"Today's agreement with member states ... marks another significant step in realising the Commission's overall strategy to tackling Europe's bee decline," EU health chief Tonio Borg said in a statement.
Unlike the banned neonicotinoids, fipronil is not widely used in Europe, with only three other EU countries currently using it for maize production besides Spain and Romania, the Commission said. (Additional reporting by Victoria Bryan in Frankfurt; editing by Claire Davenport and David Cowell)