Barnsley striker Cauley Woodrow tweeted that Barton confronted the team's manager Daniel Stendel in the tunnel following a 4-2 loss for Fleetwood. Woodrow claimed Stendel was left with "blood pouring from his face" but the tweet has since been deleted.
A South Yorkshire Police spokesman told Britain's Press Association that "we are aware of something that has taken place in the tunnel after the game and we are investigating." Neither manager spoke to media after the third-tier match.
Barnsley released a statement saying: "The club can confirm there was an alleged incident in the tunnel area that took place following the conclusion of today's match, which South Yorkshire police are currently investigating.
"The club is assisting the police with its enquiries and, as a result, we are not in a position to make any further comment at this time."
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