England's Euro 2020 qualifier against Bulgaria was stopped on two occasions following complaints of racist chanting in the stands.
The visiting coaching staff reported regular alleged monkey chants made towards England players during the first-half in Sofia.
As part of the official protocol, if the game was halted for a third time, then it would be halted but the qualifier did last the full 90 minutes.
Following the final whistle, the Football Association released a statement, it read: "The FA can confirm that England players were subjected to abhorrent racist chanting while playing in the Euro 2020 qualifier against Bulgaria.
"This is unacceptable at any level of the game and our immediate focus is supporting the players and staff involved.
"As we are sadly aware, this is not the first time our players have been subjected to this level of abuse and there is no place for this kind of behaviour in society, let alone in football.
"We will be asking UEFA to investigate as a matter of urgency."
Referee Ivan Bebek held discussions with England manager Gareth Southgate and captain Harry Kane before the first stoppage, which resulted in an announcement of the public address system.
"Because of racist behaviour which is interfering with the game, the referee has indicated he may have to suspend the match.
"Please be in no doubt that the game may be suspended and abandoned if racist behaviour continues," was the message read out to the crowd.
Despite this, the chanting continued towards England's black players, with defender Tyrone Mings being the recipient of alleged monkey chants when each time he touched the ball.
Upon a second complaint from England's staff to the match officials, the match was stopped once again.
At this point a group of young home supporters, all dressed in black, left the stand, although it was unclear if they were ejected or left of their own accord.
During the half-time break Southgate was seen in discussions with Uefa delegates, while Bulgaria captain Ivelin Popov spoke with the fans in the stands.
Fellow goalscorer Raheem Sterling tweeted after the match: "Feeling sorry for Bulgaria to be represented by such idiots in their stadium. Anyway.. 6-0 and we go back home, at least we did our job. Safe travel to our fans, u [sic] guys did well."
Southgate told ITV: "I have to say the officials were onto everything quickly, we reported everything immediately when we heard things, we had constant communication with official and referee, I was in contact with the players in the first half in particular and at half-time.
"We know it's an unacceptable situation; I think we have managed to make two statements, really, by winning he game but we have raised the awareness to everybody of the situation to have the game stopped twice.
"I know for some people that won't be enough but, as a group, we were on board with that process."
England went on to win the game 6-0, with Ross Barkley and Raheem Sterling scoring two each between Rashford's opener and Harry Kane netting the sixth.
The Vasil Levski National Stadium has a reduced capacity for the game due to previous cases of racism and the showcasing of far-right symbols in the stands.