Christchurch Police are investigating two reports of a man exposing himself to teenage girls on Monday evening.

Both reports to police were of a man in a silver or white four-by-four with an orange plastic rowboat on the roof.

The first sighting was in the Saint Martins area about 4pm, the second three hours later on Dehli Street, in Cashmere.

Detective Constable Juliette Hunter says they are speaking with the victims and ensuring they are supported.

She says they would like to hear from anyone in those areas at the time who can help with inquiries.