Newcastle United are to complain over the "unacceptable treatment" their fans endured following a 2-1 defeat at Marseille in the Champions League.
The Premier League club accused French police of using a combination of pepper spray, batons and shields to subdue supporters in the wake of Tuesday night's loss at Stade Velodrome.
A club statement said: "We will be formally raising our concerns with UEFA, Olympique de Marseille and French police in relation to the unacceptable treatment of our supporters by police at Stade Velodrome following Tuesday's UEFA Champions League fixture."
According to Newcastle, travelling fans were kept inside the stadium for an hour in a pre-planned move for their safety, with groups of 500 then escorted to the metro to go to the supporters' meeting point.
However, that is when plans seemed to go awry, with the post-match operation witnessed at close quarters by Newcastle's stewards and senior staff.
Newcastle's statement said: "Once the first group of supporters was released, the police began using unnecessary and disproportionate force to stop the remainder of our fans from moving any further.
"This was actioned through a combination of pepper spray, batons and shields, with numerous supporters being indiscriminately assaulted by the police.
"Many supporters were visibly distressed, particularly in the upper concourse area of the away sector, where crushing became apparent.
"Our staff immediately addressed the matter with the police, however this had limited impact on their excessive tactics.
- Newcastle rue few minutes of 'madness' in loss to Marseille
- Aubameyang brace sees Marseille down Newcastle
- Newcastle must back up their shock win over Manchester City - Eddie Howe
"Fans leaving the stadium rightly shared their distress, frustration and anger with our staff, and we have subsequently received deeply concerning witness reports from supporters who were in attendance.
"Supporter safety and welfare should always be of paramount importance, and we strongly condemn the treatment of our supporters by the police during this incident."
Newcastle say they will contact the relevant bodies for an investigation into what happened "to ensure lessons are learned and this behaviour is not repeated" and have called on supporters to share their view of the experience.