Papua New Guinea's Police Commissioner, Sam Inguba, is being investigated over allegations he blocked a police inquiry into an alleged fraud involved one point four million US dollars..
The country's Prime Minister, Sir Michael Somare, has announced an inquiry into the allegations.
The opposition leader, Peter O'Neill, says he has documents showing the police commissioner stopped staff from travelling to Lae to investigate the case.
The case involves a claim for compensation by 26 people for loss of business due to the conflict in Bougainville.
The compensation, part of which has reportedly been paid out, was agreed to in an out-of-court settlement reached in 2004 between the solicitor-general and the finance department.
It is alleged Mr Inguba issued transfer orders to six detectives just before they were to arrest a former senior public servant in relation to the case.