Vanuatu's opposition Vanuaaku Party says it fears no government ministers will be disciplined or prosecuted over alleged links to the Phocea affair.
Before the luxury yacht Phocea was seized in Port Vila last month, government ministers were reportedly seen on the vessel.
The yacht was searched for suspected trafficking of arms and sale of Vanuatu diplomatic passports, and reports say drugs were found which had been brought onto the boat from the Port Vila area.
The Vanuaaku Party alleges that the suspension of the country's only officer trained to investigate fraud and international crime, Andrew Kalman, shows that the government wants to shut down a possible probe of these ministers.
Police have declined to comment, referring the matter to the prime minister, Sato Kilman, who is abroad.
Observers say the prime minister's silence may be due to the politicians in question having repeatedly rescued him in the face of a motion of no confidence.
Mr Kalman plans legal action over his surprise suspension, which he put down to greed and special interests.