A former chairman of the Humberside Police Authority has been arrested in Northern Ireland on suspicion of gross indecency and other offences.
Mr Bayes has served on Hull City Council for 12 years
Hull City Councillor Steven Bayes, 45, was detained in the centre of Belfast on Monday morning. He has since been released on bail.
Police in Belfast would only confirm a 45-year-old man had been arrested.
Mr Bayes is hoping to become Labour's candidate for Hull East at the next election when John Prescott steps down.
He is a Labour member of Hull City Council representing the Orchard Park and Greenwood ward.
As part of the investigation, Humberside Police have searched the Labour Party offices and lounge at Hull's Guildhall.
A spokesman for the force confirmed: "We have been asked by the Police Service of Northern Ireland to assist with inquiries."
A Hull City Council spokesman said: "It is a matter for Humberside Police and we do not intend to make further comment at this stage."