Police are trying to find a man who allegedly performed an indecent act while on a walkway in Nelson.

The incident happened on the walkway on Annesbrooke Drive about 8am on May 11.

Police say the man is of a medium build, in his 20s to 30s, and has short dark hair and tanned skin.

He was wearing dark coloured clothing and drove a black van with a large, fluffy, black dog inside.

Anyone with information that could help in identifying the person, is asked to contact Police on 105 and quote file number 220512/3662.

Alternatively, information can be given anonymously via Crime Stoppers on 0800 555 111.