The Green Party is tight-lipped on the cost of an investigation into suspended MP Darleen Tana. 

The MP has been stood down since March 14, while an investigation takes place into her involvement into allegations of migrant exploitation at her husband's business. 

Green Party co-leader Chlöe Swarbrick told Mike Hosking “Every political party has funding that they can use at their discretion.” 

Swarbrick said “Obviously we would prefer that we weren't doing this investigation” 

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