Deputy Prime Minister Winston Peters announced last Friday that the "first round" of legal proceedings had ended.

The National MPs and staff Deputy Prime Minister Winston Peters filed legal proceedings against over the leak of his superannuation overpayment are seeking court costs from him.

Peters announced last Friday the "first round" of legal proceedings had ended and dropped his discovery attempt against two journalists also caught up in the affair.

He indicated he would soon move into a "second phase" of proceedings against the six National Party MPs named in the proceeding: Opposition Leader Bill English, National's deputy leader Paula Bennett, MPs Steven Joyce and Anne Tolley, and former staffers Wayne Eagleson and Clark Hennessy.

"They have unwittingly provided on oath information beyond what I was entitled to receive from the documents, which also provides enough information to formulate proceedings against those involved in the privacy breach," Peters said in a statement.

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Last year, it emerged Peters' superannuation had been overpaid for several years. After he was made aware, Peters paid back $18,000.

It subsequently emerged that both Tolley and Bennett's office had access to this information, but both have denied having anything to do with the leak.

The National defendants are understood to have provided sworn affidavits attesting to their innocence.

Paula Bennett said their lawyers had suggested seeking costs from Peters and that they had agreed.

A court memorandum seen by Stuff suggests the matter of costs was brought up by Peters' lawyers.

As Peters had not filed any other proceedings as part of his "second phase" they were looking to move on from the case.

Bennett hoped they could reach an amicable settlement with Peters, instead of using a court date - March 5 - which was still available to the case if needed.

Peters has yet to respond to a request for comment.