West Brom have pledged to investigate the pockets of crowd trouble that occurred during Chelsea's 1-0 victory at The Hawthorns on Friday and punish any supporters found to have sold their tickets to travelling Blues fans.
West Midlands Police have confirmed they made nine arrests -- seven men for pitch incursion, one for a public order offence and one for criminal damage -- following the win that saw Chelsea crowned Premier League champions for the second time in three seasons.
Chief inspector Nick Rowe said: "Overall it was a great evening match with an intense atmosphere, the majority of fans were really well behaved and enjoyed the game, with only relatively minor issues dealt with by officers."
Chelsea were allocated 2,773 tickets for the match but when it became clear that the title could be won at The Hawthorns the demand from Blues fans to attend the game increased dramatically, and some West Brom supporters are alleged to have illegally sold their tickets in the home end despite club warnings.
"We made it plain with our warnings before the game that any of our supporters who could be traced selling on tickets to visiting supporters faced sanctions from the club," West Brom chief executive Martin Goodman said in a statement.
"We will continue that process next week. Naturally, it is a matter of great disappointment for all at Albion and our thousands of genuine fans that a tiny minority would put profit before backing their team.
"We will also co-operate fully with police to help identify anyone clearly guilty of disorder offences during the disturbance."
Goodman added that any West Brom supporters found to have been involved in the crowd disorder will be banned by the club regardless of police action.
"I would add that we hope that these brief and isolated incidents will not detract from the club's performance on a huge night in football," he added. "On the pitch, the team could not have done more and I am sure all Albion fans were proud of a terrific performance.
"Off the pitch, we coped with enormous demands in staging a game of such importance and have been rightly praised for how we delivered."