A former Australian Border Force customs officer who was diagnosed with PTSD after being exposed to horrific child abuse materials while patrolling was told his worker's compensation payments would be cancelled after surveillance footage showed him walking his therapy dog and speaking at an event.

Mike Pritchard was told on Tuesday by a member of his treatment team the federal government's workplace insurer Comcare was cancelling his psychological injury claim, meaning his treatment - $1500 a month worth of GP, psychologist and psychiatrist visits, plus mental health medications - would no longer be covered.

Kathy Pritchard, with husband Mike's therapy dog, says she is "tired of the fight". Credit:Trevor Collens

It comes as figures reveal Comcare is rejecting two out of every three claims for psychological injury.

At a meeting with his case manager on Wednesday, Mr Pritchard and his wife Kathy were shown images taken by a private investigator of him walking the dog, buying milk, talking on the phone and speaking at an event, and was asked to justify his ongoing compensation payments.