The incident occurred at about 1.30am when two teenage females were approached by a man in McDonald’s on Blake Street.
The man then followed them to a bench outside the entrance to Museum Gardens and allegedly sexually assaulted one of them near some benches on the river path close to the steps at Dame Judy Dench walk.
The area of the incident has been cordoned off to allow for forensic examination and searches.
There will be some inconvenience to the public whilst the scene is examined and we thank the public for their patience.
Following the incident the man was last seen walking off in the direction of Scarborough Bridge along the river path.
He is described as a white, in his mid 40s, around 5ft 10 tall, with a medium build and a bald head. He was wearing a white jacket over a shirt and blue denim jeans. He spoke with an eastern European accent.
It is believed that he may have been with two other men before entering McDonald’s.
Police need to trace witnesses who may have been in McDonald’s at around 1am this morning and in the vicinity of the river path near Judy Dench walk, or walking across Lendal Bridge between 1am and 1.30am.
Alternatively, information can be emailed to YorkCID@northyorkshire.pnn.police.uk
If you prefer not to give your name, Crimestoppers can be contacted anonymously on 0800 555 111.
Please quote reference number NYP-17082014-0070 when passing information about this incident.