Bowel Cancer New Zealand's slamming the government over lack of transparency around the bowel cancer screening debacle.

An error has meant around 15,000 people have missed a potentially life-saving screening.

Initial reports suggest more than 30 people left off the invitation list for the Waitemata DHB pilot have since developed bowel cancer.

Bowel Cancer New Zealand spokesperson Sarah Derrett told Kate Hawkesby it's disturbing how difficult it's been to find out the full extent of the blunder.

"We really need the Ministry to be very transparent and reassuring the population that this error is definitely sorted."

LISTEN TO SARAH DERRETT TALK WITH KATE HAWKESBY ABOVE