It was sparked by an incident involving Baggies midfielder Youssouf Mulumbu and Royals winger Jobi McAnuff that resulted in the latter being shown a red card for violent conduct.
The stand-off continued as the visitors were then prevented from celebrating their 3-2 victory with their own fans, with Reading boss Brian McDermott afterwards accusing the stewards of over-reacting while insisting he may appeal against McAnuff's dismissal.
Albion have defended the actions of their stewards but the FA have asked for video footage of the incident and will be reviewing referee Lee Mason's report.
Apart from Mulumbu, who was quickly ushered away from the area, no other West Brom players were believed to be involved.
Source: Team Talk
Source: Team Talk