A BBC Panorama team has been threatened following the broadcast of a documentary investigating Daniel Kinahan's involvement in boxing.
Boxing And The Mob was broadcast on Monday night.
The documentary revealed that Kinahan is still working with professional fighters as an advisor, despite distancing himself from involvement last year.
Daniel Kinahan has no previous convictions, but was named in 2018 by a High Court judge as controlling a major international drugs-trafficking network.
His prominence in boxing came into view last year when he was publicly thanked by Tyson Fury for his involvement in negotiating a blockbuster two-fight deal with Anthony Joshua.
Several boxers and connections to MTK Global have spent the week since Boxing and the Mob's broadcast defending Kinahan.
Among them is WBO middleweight world champion Billy Joe Saunders. In one of his tamer tweets, he wrote, "I have known Daniel Kinahan a long time. I have always had a very positive relationship with him. I am aware of the allegations made against him but I simply do not accept them."
Barry McGuigan - who spoke out against Kinahan in the documentary - has been at the receiving end of a torrent of social media abuse. A lot of it alluded to the untimely death of his daughter, Danika.
I have known Daniel Kinahan a long time. I have always had a very positive relationship with him. I am aware of the allegations made against him but i simply do not accept them. The media depiction is totally different from the reality.
Unfortunately i have recieved a
— billyjoesaunders (@bjsaunders_) February 4, 2021
On Friday evening, the BBC confirmed that the PSNI have warned about an unspecified threat from unnamed criminal elements in relation to the Panorama documentary.
The head of BBC Current Affairs Jo Carr said of the threat, "The BBC places the utmost priority on the safety of our teams, whose journalism plays a vital role in a free society. It is despicable and intolerable if thugs think they can muzzle a free press through intimidation.
"We will continue to throw light into even the murkiest of corners."