The Vanuatu internal affairs minister, George Wells, has suspended the head of the transnational crime unit, Andrew Kalman, amid an information blackout over the search of a yacht in Port Vila.
Police boarded the yacht, the Phocea, on suspicion it carried guns and drugs.
Mr Kalman, who was suspended on Friday while in charge of the case, says he plans to challenge the minister's decision in court.
The deputy opposition leader, Edward Natapei, says he believes something major is being covered up.
Two ministers were allegedly onboard the yacht, before it was searched, but police are refusing to comment on any detail of the case.
The leader of the Vanuaaku Party, Edward Natapei, says if the Prime Minister is not going to deal with two ministers who are allegedly involved, he should resign.
"Even the acting Commissioner of Police, who was appointed by the Prime Minister, to take over the leadership of the force, is tight-lipped about it. And he is saying that only the Prime Minister will disclose anything about the search that they carried out. So, they have not revealed any information to the public in Vanuatu."