Walkers using the Ridge Walk footpath in Scunthorpe are being warned to be on their guard following a series of indecent exposures in the area.
Patrols in the area have been increased following three reports of man exposing himself in the area between July 30 and August 8.
Officers are now appealing for any witnesses, or anyone with information about the possible identity of the man or men responsible to come forward.
The first incident happened on Thursday, July 30, between 11.25am and 11.30am in the Kingsway area, when two women reported seeing a naked man in the woods who called out to the women, whilst performing an indecent act.
He was described as white, of large build and aged 20 to 30-years-old.
The second was on Thursday, August 6, between 8.15am and 8.33am, when a bare-chested man wearing jeans and a mask was seen exposing himself in the middle of Ridge Walk.
He was described as tall and of chubby build.
The final incident happened at around 8.30pm on Saturday, August 8, when a man encountered a man who was naked apart from a base ball cap and wellington boots.
Officers attended the scene and gave chase, but were unable to catch the suspect.
He is described as white, aged 20 to 30-years-old and of slim build.
Det Insp Lee Bridgeman said patrols in the area had been increased.
He added: “We would urge anyone with information about the identity of this man or men to come forward.
“Given the similarity in the descriptions, it is likely these offences are being committed by one person.
“Humberside Police takes incidents of this nature seriously and are doing everything possible to catch the person responsible.”
Anyone with information is asked to call 101, asking for Sgt Howard Garlick and quoting crime reference numbers 2128832, 2130482 and 2130771.