A chauffeur and two police officers who drove Helen Clark's motorcade as fast as 170 kmh so the New Zealand prime minister could watch the All Blacks beat the Wallabies at rugby have been fined for dangerous driving.

Clark was a backseat passenger in the one of the three cars and has claimed she was so engrossed in reading some paperwork she had no idea how fast they were going.

Nonetheless, the illegal high-speed dash on a South island highway has become an embarrassing campaign issue ahead of New Zealand's September 17 election.