The Health Ministry's attempting to contact about one-thousand people accidentally invited to participate in bowel screening

A invitation was sent in error to more than 12-hundred people who al have - or previously had - bowel cancer.

The Ministry says investigations indicate it went to people in the Tairawhiti, Canterbury and South Canterbury DHB areas.

A computer fault failed to automatically filter them out.

Chief Medical Officer Dr Andrew Simpson says they've contacted more than 200 people - many of them being understandably upset.

Simpson says an apology letter is being sent - and the Ministry's working on a permanent fix to the fault.