Former cabinet minister Maurice Williamson's actions over a police investigation into a Chinese businessman are being slammed by fellow MPs visiting Tauranga yesterday.

The National Party MP for Pakuranga was yesterday forced to resign after it emerged he phoned police about a domestic violence complaint against Donghua Liu.

Labour MP Grant Robertson believes a higher standard of behaviour should be shown by the country's MPs. Video: Luke Balvert

In Tauranga yesterday as part of the Labour Party's pre-election visit, along with Tamati Coffey, Tauranga candidate Rachael Jones and party officials, Wellington Central MP Grant Robertson says the embattled MP has been around too long and should know better.

He has little sympathy for the former Government minister and his resignation.

'He has clearly done the right thing by resigning, but he did the wrong thing in the first place.

'A minister is not meant to interfere in the police investigation. Everyone knows the police should be free to go about their jobs – Maurice Williamson intervened and he should go.”

Prime Minister John Key made the announcement after police confirmed Williamson contacted a senior official in January 2014 about Liu, saying: 'ministers cannot make a phone call when there is an ongoing prosecution”.

'The moment he made the phone call he crossed the line,” said the Prime Minister.

'As a result of the phone call police reviewed the file, and that review would not have taken place if the phone call hadn't taken place. In my view that is a poor judgement call.”

Liu was arrested in December following an incident with his partner and her mother at the Boulevard Hotel in Auckland. He is charged with male assaults female and assault with intent to injure, and is due back in court in June.

In an interview with John Campbell on TV3 last night, Williamson insisted he and Liu are not friends and he was simply doing his job as an MP in making the call.

'I wanted to establish for the sake of these people, whether they were still facing prosecutions or not.”

But he then admitted to owning a holiday home next door to Liu in Pauanui and helping him gain citizenship in 2010.

Grant believes a higher standard is required by ministers, and it is the Prime Minister's job to make sure they follow the rules.

'John Key came into government saying he had increased the standard of behaviour of ministers, but we have seen consistent behaviour of one minister after another not playing by the rules,” says Grant.

Williamson's resignation means he loses his ministerial portfolios, one of which is picked up by Tauranga MP Simon Bridges.

Simon takes on the Customs and Statistics portfolio from Williamson until a minister outside of cabinet is appointed – expected to be next week.

Simon says it is saddening when a minister resigns in circumstances such as Williamsons, but he is looking forward to the extra workload in what are 'interesting portfolios”.

'Customs is a significant one, as looking after our borders is a very important role given that we are such a trading nation.

'And Statistics is also important in understanding what's happening in our economy and various other areas of our lives,” says Simon.

'This is some more work in the short term, but with that goes some additional interest and in some significant areas.

'These are temporary appointments and the Prime Minister clearly indicated that he will be appointing a new minister in the near future.”

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