A swath of farmland around a giant nickel and cobalt mine in Madagascar has been contaminated by pesticides that have wiped out local bee populations, a group of farmers claimed Tuesday.

The Ambatovy mine, located about 80 kilometres (50 miles) east of the capital Antananarivo, is Madagascar's largest foreign investment, built at a cost of about $5.5 billion (7.2 billion euros).

Jean-Louis Berard, the secretary of a local farming and beekeeping association, said a 30-kilometre (20-mile) strip of farmland around the mine has been devastated by Ambatovy's spraying of pesticides to reduce mosquito populations that pester workers.

"According to our estimates, 1,000 tonnes of rice and 40 tonnes of honey are lost annually," Berard said.

Ambatovy did not immediately respond to a request for comment but has previously defended its environmental stance and claims to be in compliance with the highest standards for protecting the area's broad biodiversity.

The mine says it will create 15,000 direct and indirect jobs.

Berard's association says two pesticides have caused die-offs at hundreds of beehives and caused other serious environmental damages around the mine.

According to Ambatovy's website, construction at the mine was due to finish earlier this year. Ambatovy's main shareholder is Canadian mining giant Sherritt International, but it also benefits from Japanese and South Korean investors.

On Friday, it secured a six-month, renewable operating licence, but was asked to pay a $50-million deposit to cover potential environmental damage.

Tuesday's claims are the latest in a string of complaints about the mine's environmental impact.