Labour MP Kris Faafoi is up in arms over the cost of refurbishment work at his former employer's headquarters.

It's emerged TVNZ now faces an over 60 million dollar bill for the cost of its Auckland office fit out, almost 24 million dollars more than its original budget.

Unforeseen factors around weather tightness and seismic strengthening are being given as factors for the cost increase.

Kris Faafoi said what started out as a medium sized project has now turned into a whopper.

"I would have hoped that someone would have done some work to see if there were any nasties behind the gib there at TVNZ, but it seems like they didn't and now it's going to cost TVNZ another $25 million dollars which is huge."