Prime Minister Bill English says his ministers should not have been told about Winston Peters' superannuation overpayments. However, he does not believe the leak came from within the Beehive or the National Party.

English said he was concerned about how the matter became public and he would take any leak "very seriously".

"I have no tolerance for leaks of this nature. Mr Peters is understandably concerned about how the matter became public and so am I."

He said Ministerial Services would look at how the information was handled within the Beehive.

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He said it was up to the chief executives of Government departments to decide what should be notified under the "no surprises" policy.

"They do this carefully and in good faith. On this occasion, however, given the personal and confidential nature of the information, it would have been better for the ministers not to have been advised."

He said Anne Tolley and Paula Bennett were told there was an issue but it had been resolved to the satisfaction of the Ministry of Social Development.

"Tolley advised my chief of staff who made the judgment that it was not necessary for me or anyone else to be informed.

"I believe that the leak did not come from within the Beehive or the National party. The two ministers and my chief of staff have assured me of that. I would take any leak very seriously."