Papua New Guinea Prime Minister Sir Michael Somare has admitted he stopped an investigation into PNG's finance office, but says he did so on bad advice.

Radio Australia's Firmin Nanol reports from Port Moresby that the inquiry was trying to trace the disappearance of $US370 million which went missing from the finance department in April.

Sir Michael says he wanted the inquiry suspended temporarily pending an interim report, and says he was badly advised into signing documents to disband it.

He says he now regrets having had what he called too much trust in the public service.

"My intentions were misconceived by the bureaucracy and letters and instruments prepared for my signature to effect this suspension did not reflect this," he said.

"I erroneously signed these documents during my haste (in) preparing to go to my home province".

The inquiry has now been reinstated to complete its investigations.

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