The New Zealand Police are stressing that the investigation into National MP Todd Barclay is closed because of a lack of evidence.

The Prime Minister has admitted this afternoon he gave the police a statement, which he has now released, that damns his Clutha-Southland MP.

He said he told the police Barclay had told him he had recordings of his staff criticising him in February last year.

READ MORE: English confirms he told police about Barclay secret recordings

Police dropped the investigation into Barclay for allegedly recording his staff, after he refused to cooperate and denied a recording existed.

This afternoon Police said the case was reviewed by their legal section but there was not enough evidence to press charges or carry out search warrants.

Police said the file will remain closed unless new evidence comes to light.