Radio New Zealand - Te Reo Irirangi o Aotearoa

National MP Nick Smith says he would recognise the person he believes secretly recorded him.

Dr Smith was one of three National Party MPs recorded without their knowledge at the party's conference last weekend. Others were Bill English and Lockwood Smith.

Dr Smith told Morning Report the person said he was a member of the Young Nats and asked for his views on KiwiBank, Working for Families and nuclear energy.

He said there will have to be greater security at party events in future and MPs will be less frank with young people.

National blames Labour for "dirty tricks". Labour wants an apology.

National has requested security footage of the event. It says that rubbish at party leader John Key's Helensville electorate office appears to have been ransacked for the second time in a month.

Diversion tactic, says Cullen

Deputy Prime Minister Michael Cullen says National has no real basis for what he calls its "wild claim", which he describes as a diversion tactic.

Dr Cullen says photographs distributed by National of Mr Key's rubbish look like a dog has gone through it looking for leftovers.

Mr Key said on Wednesday the recordings were not made by genuine delegates. He said it has become clear Labour's tactics include bugging conferences and personal conversations, rorting the electoral law and condoning the stealing of emails.

Prime Minister Helen Clark says Mr Key's paranoia is getting the better of him.

Legality of recordings

A legal expert says it would be difficult to convict a person for secretly recording National Party MPs at a cocktail party.

University of Canterbury associate Professor of Law Ursula Cheer, told Morning Report it is a criminal offence to secretly record a conversation.

But she said it is allowed if the person making the recording is part of the conversation, or if the person being recorded could have been expected to have been overheard.