The Prime Minister is seeking assurances today that no New Zealand First MPs were under instruction to nudge National's Mark Mitchell out of a local project.

Mitchell has claimed NZ First MP Jenny Marcroft told him to pull out of a group for the Mahurangi River Restoration Project in Rodney and stop questioning Regional Development Minister Shane Jones about the fund or it would not get funding from the Provincial Growth Fund.

Mitchell claims Marcroft said she was speaking on behalf of a minister but NZ First leader Winston Peters said Mitchell's account was "a misunderstanding" for which Marcroft later apologised and has denied any NZ First ministers were involved.

READ MORE: National accuse NZ First of holding regional projects to ransom

Jacinda Ardern told Mike Hosking New Zealand First has said it's a misunderstanding.

"There is now a bit of 'he said, she said'. [New Zealand First's statement] says no MP was under any instruction by NZ First ministers.

"I have to take a minister at their word, in fact Parliament has to take members at their word."

She said the Provincial Growth Fund was funding numerous projects identified by the former National Government. "This is not a political fund. That's something I will be very keenly ensuring remains the case."

She said she took Peters at his word when he said it was a misunderstanding and no NZ First ministers were involved.

"If ministers are saying to me they issued no instruction I have no reason to disbelieve that. I have an absolute expectation that, as all parties involved in Government, each leader does their best to make sure they maintain a high standard and I'm sure Minister Peters will be doing that too."

Ardern said dealing with Marcroft was Peters' job. "I find it challenging enough to make sure I keep control and oversight of my own party and my own ministers. That's where my jurisdiction sits."

The Minister responsible for the Provincial Growth Fund, Shane Jones, says it's nothing to do with him.

"It sounds like a local spat. But if you're asking me am I'm monstering anyone over the the growth fund, absolutely not."

LISTEN ABOVE AS JACINDA ARDERN SPEAKS WITH MIKE HOSKING