Labour Party MP Phil Twyford says sending out electioneering e-mails from the Parliamentary e-mail system was a genuine mistake, for which he is sorry.
Local Government Minister Rodney Hide has complained to Parliamentary Services about e-mails sent to about 1000 people on Thursday encouraging people to vote for Len Brown for Auckland mayor.
Mr Twyford says the e-mails probably did not cost taxpayers a penny, but the rules clearly state that Parliament's systems should not be used for electioneering
He says he should have used his personal e-mail address.
Mr Twyford says Parliamentary Services has told him he has a case to answer and the matter will be referred to the Speaker.
Mr Hide says individual MPs should not use their taxpayer-provided resources to influence local government elections in any way.