Dr Worth's resignation' />

Richard Worth has resigned from Parliament, saying he is the victim of "hearsay, character assassination and scuttlebutt".

Dr Worth's resignation takes immediate effect, and follows him quitting as a Minister last week following a serious sexual allegation from a Auckland-based Korean businesswoman.

The list MP said the decision was both personal and for the welfare of the National Party "which I love and have served to the best of my ability for the past nine years".

John Key called Worth's resignation "a sensible course of action" under the circumstances.

Mr Key said he was notified this afternoon.

"The decision gives the country an opportunity to move forward and focus on the issues that matter.

"There are important challenges facing New Zealand, and they will continue to have the Government's full attention.

Mr Key said he looked forward to the next man on National's list, Cam Calder, replacing Dr Worth as an MP.

Worth lamented a public and political character assassination which had made his position untenable.

"It would be easy for me to be bitter about the avalanche of rumour and innuendo that has led me into making this decision which I regard as being in the best interests of my party," he said in a statement.

"I wish only to restate that I have not committed any crime, and I remain confident that when the true facts are established I will be cleared of any and all allegations of criminal conduct. I will steadfastly defend myself in respect of those allegations."

Dr Worth said in the statement he was finding it impossible to defend himself in the public and political arena because of the character assassination.

"Like most of us, if we are honest, I may at times during my life have said and done things which, when analysed in the cold light of day, may seem to have been unwise. As I said last week, like any other citizen I am entitled to the presumption of innocence until proven guilty.

"I could spend the future bemoaning the unfairness of a campaign which has Labour's fingerprints all over it. But that is not my nature. The campaign has been run against me by people who are unable or unwilling to back their claims with credible evidence of criminal activity.

"I went into politics to make a contribution to New Zealand. I can see that it is no longer possible for me to do that through politics, so I am now choosing to follow another positive path.

"Helping New Zealand win international trade will be the focus of my future activities.

"I believe I may make a greater contribution through my business activities than by attempting to remain in politics in what would clearly be an untenable position, and hoping to be forgiven for things of which I am innocent.

"My conscience is clear. Those who have chosen to try to ruin my reputation should perhaps now examine theirs.

"My wife and family stand behind me in this decision, as they have stood by me, together with our friends, in the past difficult weeks. Their loyalty and love has been a timely reminder for me about what is truly important in life.

"This whole episode has taken a toll on me personally, and this is why I have made myself unavailable to the media and will continue to do so. I would ask that media now respect my right to privacy and allow me to get on with my life.

"That is all I wish to say. I am moving forward on a new path."