The Lions could be facing disciplinary action after ugly scenes marred Boro's 3-2 win at The Den.
Referee Chris Sarginson had to stop the game on two occasions and even considered calling the match off after Boro goalkeeper Jason Steele and the assistant referee were the target of bottles and other objects thrown from the crowd.
The trouble began after the assistant allowed Scott McDonald's second-half goal to stand despite the player appearing to be in an offside position.
The FA are also probing disturbances at the Black Country derby between West Brom and Wolves.
A spokesman said: "We are awaiting the match officials' report and we will be seeking observations from both clubs."
Source: PA
Source: PA