New Zealand First believes it is not tenable for Mike Sabin MP to remain chairperson of Parliament's Law and Order Select Committee while Police investigate an assault allegation against him.

'While there is a presumption of innocence in our judicial system there is also something also called the Westminster tradition,” says the Rt Hon Winston Peters, Leader of New Zealand First.

'New Zealand First isn't calling on Mr Sabin to resign his seat, yet, but once Police decided to investigate he should have stood himself down as both Chair and a member of the Law and Order Select Committee as well as from the Justice and Electoral Select Committee.

'If he will not act then the Prime Minister must and should have by now.

'We are surprised Mr Sabin has not done the honourable thing or been made to do so. The public will view as incompatible an allegation of criminality and his $162,000 role chairing the Law & Order Select Committee.

'Then again this raises some uncomfortable questions whether Mr Key, as Leader of the National Party or senior Ministers in that Party, knew about Police investigation before Mr Sabin was appointed to the chairmanship in October.

'If National knew of the Police investigation before Mr Sabin was given his role chairing Parliament's Law and Order Select Committee then it makes it inexplicable and inexcusable,” Mr Peters said.