National's Housing spokesperson is calling the growth in staff numbers at Kainga Ora 'unbelievable'.

A leaked briefing obtained by Newstalk ZB reveals the agency plans to hire nearly 500 more full-time staff in the coming year.

It's since gone back on that figure, saying it needs 465 staff and almost half will be to fill existing vacancies.

Chris Bishop told Mike Hosking it comes at a time when only 21 net new state houses have been built in the past year.

He says Kainga Ora is increasing staff and has a massive debt blowout, but can't actually build many houses.

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