A live Japanese hand grenade was found at Hapuna Beach State Recreation Area Tuesday, the third explosive discovered at the Hawaii island site since an unexploded ordnance cleanup was started in early September, the state Department of Land and Natural Resources said.

Gov. Neil Abercrombie’s office, criticized for suspending Hawaii environmental and land use law to facilitate a variety of ordnance cleanup projects, pointed to the munitions finds as an example of the "effectiveness" of the state’s actions.

Two grenades and a live Japanese 57 mm mortar have been located and detonated, officials said.

Without the emergency proclamation, it is likely that one of the hand grenades "would still be on the beach today," the governor’s office said on its website.

The Sierra Club Hawaii Chapter and several other environmental and cultural groups urged Abercrombie on Monday to withdraw an emergency proclamation that he made to help the Army Corps of Engineers remove unexploded ordnance.

Abercrombie declined.

The environmental and cultural groups say Abercrombie misused his emergency powers in June when he suspended about two dozen state land use and environmental regulations for five years to help the Corps get to and remove discarded military explosives.

Abercrombie invoked the state law intended to respond to enemy attack and natural and manmade disasters to help contain unexploded munitions that in some cases date to World War II-era military training.

The environmental and cultural groups said that while the Abercrombie administration might have been well-intentioned, suspending the land use and environmental regulations was ill-advised and undermined transparency, accountability and community involvement.

Abercrombie’s office said on its website that "the state considered the risk to public health, safety and welfare to be too great to require the Army Corps of Engineers to wait for an environmental assessment to be done before disposing of any munitions found on state land."

The mortar’s Japanese origin "is not surprising because back in the days of World War II, they (U.S. troops) were training, and they had to familiarize themselves with the weapons of the enemy," Army Corps spokesman Joe Bonfiglio said last week.

The park was part of Waikoloa Training Area, which was used to train soldiers for Pacific island invasions, Bonfiglio said.

The grenade was found in the same area where the 57 mm mortar was found Sept. 15, north of the cabin area and southeast of Hapuna Prince Hotel.

The latest grenade was found on the ground and in the open, the land department said. Workers moved it to the vicinity of where the Japanese mortar was detonated, and the grenade also was detonated.

No evacuation or park closure was required since the closest public access is a road about 200 yards away, the department said. A live hand grenade discovered Sept. 8 was the first object found in the park.

"Scanning" for more ordnance will take place through all of Hapuna Beach State Park past Waialea to Puako Road, officials said. The Waialea section will be done from November to December. The entire phase of this project will not be completed until mid-January 2012, the state agency said.