Australian soldiers have cleared more than six tonnes of unexploded hand grenades and mortars from a World War II battle site on the island of Bougainville, east of Papua New Guinea.

Watch the Australian Department of Defence VIDEO Here

The huge haul of munitions came in just the first week of Operation Render Safe 2014.

Report from Liam Cochrane ABC network Australia

Photo from the Australian High Commission  PNG

The Australian-led international mission is clearing potentially deadly munitions from the villages and food gardens around Torokina, on the west coast of Bougainville.

The Australian Army said the sheer amount of rusty old munitions surprised even seasoned explosive ordnance disposal (EOD) experts.

“They are mostly two-inch-high explosive mortars and hand grenades, in varying conditions, left in place after the war,” EOD operator Warrant Officer Class Two David Austin said.

An Allied air base was built at Torokina by the US in 1943 and was the launching place for Australian ground attacks against the Japanese in 1944-1945.

More than 500 Australians died and 1,500 were injured in the Bougainville campaign.

Seventy years later, the Australian army has returned to clean up the deadly remnants of war.

More than 500 Australian military personnel are involved in Operation Render Safe 2014, with support from HMAS Choules, an MRH90 helicopter, landing craft and amphibious vehicles.

With little infrastructure at Torokina, soldiers have landed vehicles on the beach and trekked into the jungle to look for unexploded ordinance.

Despite five months of awareness-building activities, there were criticisms of the munitions clearance by some former combatants in the more recent conflict on Bougainville.

Australia’s role on Bougainville is still a sensitive issue due to the civil war in the 1990s, sparked by disputes over the Panguna mine, operated by Rio Tinto subsidiary Bougainville Copper Limited.

“Former combatants have said that this operation is a breach of the Bougainville Peace Agreement, but I had explained to them that the operation… enhances the peace that the people of Torokina want,” said Patrick Nisira, vice-president of the autonomous government of Bougainville.

Local police help soldiers locate storage pits

Australian army personnel said the reception on the ground had been friendly.

“The people of Bougainville have been most welcoming and we have been working very closely with them to identify explosive remnants of war which pose a threat to local communities,” operation commander Captain Jay Bannister said.

Members of the Bougainville Police Service and locals have helped soldiers locate the munitions storage pits, with assistance from explosives experts from the US, UK, Canada, News Zealand and Solomon Islands.

“As well as helping the community, this is a great training opportunity for the younger EOD guys,” Mr Austin said.

“For the past 10 years we have been focused on the Middle East region but this gets us back to the grass roots fundamentals of our job.”

The mortars and hand grenades were stacked in pits and destroyed by a controlled blast.

Operation Render Safe 2014 will end on 8 November.

Previous Operation Render Safe missions have removed unexploded ordnance from Solomon Islands and Rabaul in Papua New Guinea.