Wellington City Council has admitted personal details of up to 120,000 people were inadvertently released by its parking contractor.

The council's parking services contractor Tenix Solutions released "bulk" personal information about 120,000 parking tickets issued over the last two financial years, the council said in a statement today.

The breach happened in response to an information request for publicly-available information from Tenix about council parking enforcement data spanning a two-year period.

However, parking ticket information released on three separate disks contained personal details about vehicle owners' names, addresses and registration numbers.

The person who made the request contacted the council on November 19 when he realised it wasn't the information he had asked for.

Since then, he has cooperated fully with investigators working on the breach and returned all of the data, the council said.

Council chief executive Kevin Lavery said he had instructed Tenix to carry out a full review to assure the breach would never happen again.

"I would like to unreservedly apologise to those individuals whose personal information has been disclosed and, again, thank the requestor for returning the information.

"I have been clear with our contractor that its performance in this event was woeful. We should all have every confidence that our personal information is secure and that there are processes and systems in place to ensure this does not happen again."

- APNZ