Police have completed an inquiry into former National Government minister Richard Worth and will not bring any charges, they said this afternoon.

Dr Worth resigned after one woman laid a complaint of a sexual nature with police, and another woman claimed he harassed her with text messages and phone calls.

Inquiry head Detective Inspector Paul Basham said police had completed a "careful and thorough investigation into the matter", which included peer review by a senior CIB officer and assessment by police legal advisers.

A spokesman added: "Having completed the investigation, the police have determined that there is no basis for proceeding with any criminal charge against Dr Worth."

Police interviewed Mr Worth in Auckland in June.

After the sudden announcement of Dr Worth's resignation as a minister in June, Prime Minister John Key said that he would have sacked him had he not resigned.

"His conduct does not befit a minister, and I will not have him in my Cabinet," Mr Key said at the time.

He also said then that he would probably reveal why he had lost confidence in him but he did not want to contaminate a police investigation. He later said he would not comment on the issue.