Williamson's roles split amongst three
Christchurch Central MP Nicky Wagner has been promoted to a Minister outside Cabinet after Maurice Williamson was forced to resign last week when it emerged he called police about an ongoing investigation.
Williamson stood down on Thursday after it became public that he telephoned police on behalf of a wealthy Chinese businessman and National Party donor, Donghua Liu, who was facing domestic violence charges.
Wagner will take over his Customs, Statistics, Associate Conservation, and Associate Canterbury Earthquake Recovery portfolios.
Housing Minister Nick Smith will take on Williamson's old Building and Construction portfolio, and Immigration Minister Michael Woodhouse will also take over Land Information.
Prime Minister John Key thanked all three for taking on the extra responsibilities.
"Nicky has been an MP since 2005, and has done a great job in Christchurch and in chairing the Local Government and Environment Select Committee.
"As a minister I expect she will treat her new portfolios with the same hard work and enthusiasm," Key said.
The Governor General will swear in Wagner on Wednesday.
Wagner takes the associate earthquake minister portfolio of Amy Adams, who still holds on to Environment and Communications and Information Technology.
Liu was arrested in December following a domestic violence incident with his partner and her mother at Auckland's Boulevard Hotel, which Liu owns.
He pleaded guilty to the two charges on April 1, and was released on bail. He is due back in court next month for "monitoring".
In 2010, Williamson lobbied ministerial colleagues heavily on behalf of Liu's citizenship bid. The immigration minister at the time, Nathan Guy, subsequently approved Liu's citizenship, against official advice.
Williamson said he got wind of Liu's arrest early this year and in January called police on his behalf, "to clarify the status".
An email chain from earlier this year, released by police, shows Williamson's call prompted a review of Liu's case, but had not pressured police into dropping the charges.
Acting Deputy Commissioner (Operations) Grant Nicholls said he was satisfied that staff "acted with best intentions in their interactions with Mr Williamson and the prosecution guidelines were followed in the case".
The emails show Inspector Gary Davey handled Williamson's inquiry, after Superintendent Mike Clement asked him to explain the police position.
Briefing his colleagues afterwards, Davey said Williamson had told him he wanted to ensure police were on "solid ground" because Liu had invested a lot of money in New Zealand.
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