Five Chinese workers were hurt after armed villagers stormed a nickel mine in Papua New Guinea, damaging equipment and forcing it to close, a report said Thursday.

PNG police said they were investigating the attack after the staff were injured when the villagers charged into the Kurumbukari mine southwest of Madang on Monday morning, PNG's The National reported.

"Five Chinese employees got injured with one receiving 14 stitches," the newspaper quoted an unnamed Ramu company representative as saying.

Mining machinery was burnt and office equipment trashed, the report said, adding that Ramu NiCo president Wang Jicheng had visited the site to access the damage.

The Kurumbukari mine is part of the US$2.1 billion Chinese-run Ramu Nickel project, which produces 31,000 tonnes of nickel and 3,000 tonnes of cobalt annually on the northern coast of the Pacific nation.

The project's Basamuk refinery site was attacked by PNG mine workers in 2009, injuring five Chinese and three locals.

The Chinese government-owned Metallurgical Group Corporation, known as MCC, is the majority owner of the project. Local partner Highlands Pacific owns an 8.56 percent stake.

The National reported that while the company was looking into what sparked the attack, earlier investigations suggested illegal migrants to the area were unhappy with the firm's hiring policies.

The Ramu representative said his firm had been trying to encourage locals to undergo training, and was trying to recruit skilled workers from outside the region "to occupy the increasing skills gap requirement so the project production is increased".

"We will continue to establish a mutual understanding and relationship with the project landowners for their long-term benefit and that of the project shareholders," the representative said.