The New Zealand Drug Foundation is defending spending up large on pro-cannabis advertising.
It's spent hundreds of thousands of dollars so far on its campaign in the lead up to the cannabis referendum.
Executive director Ross Bell told Mike Hosking campaign rules don't require the naming of private grants or donations.
He says they're playing by the rules and will comply with a spending cap once the election reporting period starts at the end of the month.
"Up until the election, we are only allowed spend about $300,000. That is about what we have raised at the moment, and we have spent that much on the campaign so far."