Progressive leader Jim Anderton has launched an extraordinary attack on the Electoral Commission for referring him to police for a possible breach of the Electoral Act.
The referral follows a complaint, brought by right-wing blogger WhaleOil, about a letter the Wigram MP sent to voters endorsing the Labour candidate Megan Woods in November's election.
If found guilty, Mr Anderton could face a fine of up to $40,000.
But Mr Anderton, who was referred to police over election advertising before the 2008 election, said he had done nothing wrong.
"Nonsense, rubbish, waste of time, waste of police resources, waste of space. It's just as ridiculous as the referral I had to police at the last election. They threw it in the bin then and they'll do it again now.