Labour Party MP Shane Jones says the Prime Minister's response to ACT's latest comments about Māori is disappointing.
John Key says the ACT Party's newspaper advertisements accusing National of pandering to Māori radicals to appease the Māori Party are factually incorrect.
Mr Key says the National Party has put race relations on a good footing in New Zealand and the latest ad campaign will not be a barrier to ACT and his party working together.
But Mr Jones says ACT's continual efforts to drum up anti-Māori feeling are divisive and deserve stronger condemnation.
He believes Mr Key ought to show a level of unifying leadership and not let ACT leader Don Brash continue to make untrue statements about Māoridom.
Mr Jones says ACT's comments denigrate the Māori Party and is surprised the Prime Minister is not defending National's coalition partner more forcefully.
The ad has also been criticised by the Māori Party and United Future, which also have support agreements with National.