Wellington City Council believes the National Party will find it difficult to identify many faces on security camera footage of a National Party conference last weekend.
Remarks by three senior MPs were secretly recorded during a cocktail party.
A council spokesman says the footage is from the function centre's stairwells, but it may not be a straightforward matter to identify those attending the function.
The National Party says it will methodically go through the footage, but will not say who it is looking for.
National MP Nick Smith said on Friday that he would recognise the person he believes secretly recorded him.
Dr Smith was one of three MPs recorded without their knowledge. 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.
National blames Labour for "dirty tricks". Labour wants an apology.