Riot police were forced to break up a mass brawl that erupted at the ACB 90 MMA event in Moscow, following the disqualification of a fighter who punched his opponent after the bell.

Former Bellator fighter Georgi Karakhanyan, 33, was vocal in the media during the build-up to his second fight under the Absolute Championship Berkut (ACB) banner in Russia, where he faced an organization newcomer in the form of 25-year-old Tumir Nagibin.

Karakhanyan had been particularly active in dishing out insults to his opponent on social media – including threats to sexually abuse Nagibin by “putting a bottle up his anus.”

The verbal attacks drew significant attention given that trash-talking before fights is not commonplace in Russia, and also led to raised temperatures at the weigh-in ceremony, where Karakhanyan continued to goad Nagibin.

A bit of tension between these two: @GeorgiMMA Karakhanyan vs Timur Nagibin #ACB90pic.twitter.com/JTABXJjrVU — Denis Geyko (@DenisGeykoRT) November 9, 2018

The fight itself, which happened on Saturday night, was no less controversial, ending with the biggest scandal of the year in Russian MMA. At the very end of the first round, Karakhanyan attempted to submit his opponent with a choke hold, although Nagibin didn't appear to be anywhere near quitting. Despite that, the American fighter of Armenian descent cried out "he is tapping" to referee Herb Dean.

In the video posted on the ACB TV YouTube channel, Dean can be heard asking the fighter "(Did) he tap?" while touching Nagibin's back.

Following the move, Karakhanyan released the choke, which seemed to shock Nagibin, who took the situation as a fight stoppage, just a second before the bell. He then looked at Dean, who could be heard saying "he didn't tap," before turning back to his opponent and landing a punch to his face.

Nagibin was eventually disqualified as a result of the attack on his opponent after the end of the round, while Karakhanyan was announced the winner.

But the drama didn’t end there, and what came next required riot police to step in and restore order.

As Nagibin was being escorted from the cage some of Karakhanyan’s fans tried to start a brawl with the fighter and his team. The scenes were filmed from various angles by fans and members of the media at the event – including RT Sport's Denis Geyko.

A mass brawl breaks out after Karakhanyan fans attack Timur Nagibin, as he is being walked away from the cage following disqualification for punching his opponent after the gong #ACB90pic.twitter.com/dLuDPhad0d — Denis Geyko (@DenisGeykoRT) November 11, 2018

Much to the credit of the riot police the scuffle was broken up in a matter of minutes – although a number of fights erupted in the stands where Armenian fans had gathered to support Karakhanyan and other fighters of Armenian origin.

Fights also broke out in the stands after Karakhanyan v Nagibin bout was stopped due to the DQ of the latter #ACB90pic.twitter.com/KZxjY3kNTO — Denis Geyko (@DenisGeykoRT) November 11, 2018

While some of those brawls looked like spiraling out of control, no serious injuries or arrests were reported.

As for the future of Karakhanyan and Nagibin, RT Sport has been informed that ACB intend to stage a rematch between the two at one of their next events. Talking to RT Sport after the event in the fighter's hotel, Herb Dean stressed that he had no intention to stop the fight and was "only checking if Nagibin was conscious."