A 30-year-old man has been arrested on suspicion of sexual assault following an incident in Manton Wood in Worksop.
The alleged incident happened on Sunday, May 29 at about 5.50am and occurred while a woman was walking along a footpath.
Patrols have since been increased in the area.
The man has been bailed pending further enquiries.
Police are still appealing for witnesses and officers would like to trace a man who was cycling in the area at the time.
He was riding what is believed to be a light blue bike and is described as white, slim, 5ft 8ins tall, clean shaven and in his 20s. He was wearing an orange hoodie, with a dark coloured hat underneath and dark coloured combat trousers.
Call Nottinghamshire Police on 101, quoting incident 198 of 29 May.