Wellington City Council has confirmed it is investigating Mayor Andy Foster over a complaint made on the day of the Shelly Bay vote.
The complaint was made two weeks ago on the day when councillors voted to sell and lease the council-owned Shelly Bay land.
Councillor Jenny Condie claimed Foster had revealed information to her which she believed he was not permitted to do.
The information was also potentially defamatory to a former officer of the council.
A spokesperson said council is “continuing to follow processes related to council code of conduct”.
Over the weekend, Foster was photographed helping the iwi group occupying the land set up tents.
Gathering at the site to pitch tents on Sunday, a group of Wellington iwi Taranaki Whānui, called Mau Whenua, announced they were "settling in for the long haul".
It comes ahead of a High Court case set down for next March challenging the legality of who owns the land.