New Zealand First leader Winston Peters is accusing the Prime Minister of spying on him with the Government Communications Security Bureau.
John Key on Wednesday accused Peters of meeting internet entrepreneur Kim Dotcom three times.
Peters on Thursday confirmed meeting Mr Dotcom three times over two years, but said he had agreed to keep them confidential.
He told reporters that the only way John Key could know about them was if he was being spied on.
"What's his informant, who is he? ... This is a surveillance matter and I want to know more about it."
John Key on Thursday denied using the GCSB to keep tabs on Peters. He wouldn't say who told him, but said it definitely wasn't a spy agency.
"I heard from an individual who's a person who's got nothing to do with National Party, nothing to do with any government agency.”
Peters said he first met Mr Dotcom to discuss his move to New Zealand and then twice more to discuss the GCSB case.