A Vanuatu opposition MP, Willie Jimmy, says the police commissioner is obstructing the constitutional and democratic rights of MPs.
The comments follow media statements by the commissioner, Arthur Caulton, that officers are taking statements from MPs after the prime minister, Moana Carcasses Kalosil, complained that some members are being offered bribes to support a no confidence motion against him.
Mr Jimmy says Mr Caulton should remain neutral and not interfere in MPs' rights.
He says the commissioner is preventing MPs exercising their democratic rights and can only take statements and carry out an investigation if there is a formal complaint.
A staffer in the prime minister's office, Letty Kaltonga, says Mr Carcasses had laid no complaints with the police.
Our correspondent in Port Vila reports a senior police officer as saying three government MPs have accused the opposition of offering them money to sign the motion against Mr Carcasses, but they could not provide strong evidence to support this.