Police are warning men to quit using a "family-friendly" park in Auckland as a place to engage in sexual activity.

Murphy's Bush

Auckland Council and police have been working to try and stop the men by removing some trees and actively monitoring Murphy's Bush, in the suburb of Flat Bush.

However, they say this hasn't deterred the offenders.

Police say engaging in offensive behaviour in public is a crime which carries a maximum penalty of $1000, and committing an indecent act in a public place carries a maximum penalty of up to two years imprisonment upon conviction.

Inspector Wendy Spiller says "it's unacceptable" and "really disappointing to hear that many of our community members are avoiding using this space due to the actions of the minority".