Workers at an AngloGold Ashanti gold mine in eastern Guinea are on strike in a dispute over year-end bonuses, Saadou Nimaga, secretary general of the ministry of mines, said on Sunday.

"The strike was triggered about a week ago but we are organising negotiations," Nimaga told Reuters.

Miners at Siguiri, around 800 km (500 miles) east of the capital Conakry, barricaded the plant's entrances and stopped a plane loaded with gold from taking off, in pursuit of their demand for a two-month bonus rather than 50 days, a worker said.

"We are demanding the departure of the mine's director general," a worker told Reuters. Bonuses are normally paid at the end of the year. It was unclear why workers did not publicise the strike sooner.

There was no immediate comment from AngloGold, Guinea's largest gold producer with an annual output of 300,000 ounces.

Siguiri is a multiple open-pit oxide gold mine and AngloGold's sole operation in Guinea. The South African company holds an 85 percent stake, according to its website, with the government holding the balance.