A football supporters group has asked police to explain the "totally unacceptable treatment" of its fans.
Boro Support claims Staffordshire Police used pepper spray on Middlesbrough fans after the match with Stoke City on 11 December.
The group said "innocent fans" had been caught up in "extremely heavy-handed policing".
The force said a number of complaints were being reviewed by its professional standards department.
In a letter to Staffordshire Police's chief constable, Chris Nobile, Boro Support's chair Mark Motley said officers should not put the public in "situations that are at best uncomfortable and at worst intimidating".