Police in Auckland are warning the public of a well-dressed man posing as a council worker, who tried to scam an elderly woman in Glen Eden.

The Caucasian man was wearing a high vis vest when he knocked on the woman's door and told her he was there to test the water pressure.

He also asked for her landline number.

Ten minutes after he left, the woman received a phone call from a blocked number, with the caller telling her he was a police officer and that someone had stolen her wallet.

He asked for her PIN number, saying he needed it to close her accounts.

Police say fortunately the woman refused and hung up on him, and then discovered that her wallet had in fact been stolen.

Police are reminding people never to give our their PIN number.