New Zealand First leader Winston Peters has ramped up criticism of Prime Minister Bill English over the Todd Barclay affair - saying English should resign.

"He's got to go, Mr English. He's got to stand down, just like Barclay. He misled the media, he misled the House in every respect he is in serious breach of his responsibilities and duties," Peters said to media before entering question time that saw further questions about English's actions.

Asked if English had lied, Peters said there was no other possible conclusion. Despite calling for English's resignation, Peters did not rule out going into Coalition with National after the September 23 election.

Barclay confirmed yesterday that he wouldn't seek re-election as Clutha-Southland MP in September, saying it was in the best interests of the Government and National Party.

The focus is now firmly on the police investigation, and English's own actions after Barclay confided he left a dictaphone running in his electorate office and had recordings of former staff member Glenys Dickson.

Before Barclay became MP, Dickson had worked for English, who held the Clutha-Southland seat for 18 years before becoming a list MP.

Amid rumours of secret recordings, former electorate chairman Stuart Davie last year texted English asking about the claims. English's February 21 response read: "He left a dictaphone running that picked up all conversations in the office. Just the office end of phone conversations. The settlement was larger than usual because of the privacy breach."

In a subsequent police interview, English confirmed the text, and said Barclay had told him he had recordings of Dickson criticising him, after he left a dictaphone on.

English's texts and statement were entirely redacted by police when they released documents to the Herald under the Official Information Act in March.

After the text was published on Tuesday by the Newsroom website, English said he couldn't recall who told him the recordings existed, but less than four hours later confirmed it was Barclay, and released his police statement.

-NZ Herald