More than 1,000 workers have gone on strike at an Indonesian gold and copper mine owned by US firm Freeport-McMoRan in a row over bonus payments, the company and a union said on Monday.

The workers, mostly truck operators, started the strike last Wednesday at Grasberg, one of the world's biggest gold and copper mines, which is located in the mountains of eastern Papua province.

The workers' union said they were angry about differences in bonus payments given to them and an engineering team at the site.

Riza Pratama, a spokesman for Freeport's Indonesian unit, said operations in Grasberg's open-pit mine had been affected by the strike but an underground mine at the site was so far unaffected.

A processing plant at the mine was still operating but at limited capacity, he said.

A member of the union, Gibi Kenelak, said that a senior company official had flown from Jakarta and spoken to the workers on Monday but the matter remained unresolved.

Grasberg has been plagued by strikes, accidents and production problems in recent years.

In 2011, a three-month strike crippled production at the mine, and workers only halted the industrial action once Freeport agreed to a huge pay rise.