Now, the US government is offering $5m for information that leads to the arrest or conviction of Daniel Kinahan and the other leaders of the Kinahan cartel.

The dramatic intervention is seen as a major blow to the sprawling criminal gang, whose drug and firearms trafficking grew out of Dublin streets to span countries around the world.

Here, Sky News looks at what we know about Kinahan, the alleged crime boss who is said to have brought "an element of terror" to the world of boxing.

Early life

Born in 1977 in Dublin, Kinahan is the eldest son of Christy Kinahan, a convicted drug dealer widely reported to be the founder of his family's criminal operation.

Kinahan has claimed he was raised in a deprived area, with serious levels of poverty and crime, which sparked his interest in boxing.

"People like me, from there, aren't expected to do anything with their lives other than serve the middle and upper classes," he said.

"Boxing is a working class sport for which I've had a lifelong love and passion."

Kinahan - who has no criminal convictions - was reportedly arrested in connection with an attack on two police officers outside Dublin's Shelbourne Park greyhound stadium in May 2001.

He was charged with assault and was initially refused bail but the charges were dropped the following January, according to the Irish Independent.

WikiLeaks revelation and arrest in Spain

In 2009, Kinahan was reportedly mentioned in a diplomatic cable sent from a US embassy in South America, in which he was described as a suspected international drug-trafficking figure.

The reference was revealed in a WikiLeaks publication of confidential US documents.

Kinahan was arrested in Spain in 2010, along with his father Christy and brother Christopher Jnr, but the long-running money-laundering case was dropped in 2020.

In 2016, it was reported that Kinahan ran a series of innocuous companies ranging from interior design firms to a cleaning business during his time in Ireland - none of which he ever filed any accounts for.

Company records showed that Kinahan declared himself to be an "upholsterer", the Irish Independent said.

Attempt to kill Kinahan amid gang feud

Kinahan fled Ireland after an attempt was made on his life at a boxing weigh-in at Dublin's Regency Hotel in 2016.

Gunmen from the rival Hutch gang disguised as armed police attempted to murder him, killing his associate David Byrne instead.

Describing the incident, Kinahan said one of the attackers was "maybe six metres from me" when he saw a gun and heard "'boom boom' shots let go".

At least 18 people have been murdered in the feud between the two gangs.

Kinahan, his father Christy and brother Christopher Jnr are all now based in the United Arab Emirates.

In May 2017, Kinahan reportedly got married at Dubai's seven-star Burj al Arab hotel.

Among the guests were Chilean druglord Ricard 'El Rico' Vega, Dutch-Moroccan mobster Ridouan Taghi, and Italian mafioso Raffaele Imperialem, according to Dublin Live.

Tyson Fury's praise for Kinahan

Kinahan co-founded the boxing management company MTK Global, which represents more than 300 fighters including Tyson Fury, Carl Frampton and Billy Joe Saunders.

In June 2020, Fury publicly thanked Kinahan for securing a two-fight deal with fellow British heavyweight boxer Anthony Joshua, in one of the most-anticipated title bouts in the sport's history.

"I'm just after getting off the phone with Daniel Kinahan," Fury said.

"He's just informed me that the biggest fight in British boxing history has just been agreed.

"Big shout out to Dan. He got this done, literally over the line. Two fight deal."

He went on: "So a big thank you to Dan for getting this deal over the line. All the best. God bless you all. See you soon."

There's no suggestion whatsoever of Tyson Fury being associated with any wrongdoing.

After Kinahan's involvement was revealed, then-Irish premier Leo Varadkar said it would be "entirely appropriate" for broadcasters not to show the planned fights.

Following the outcry, KHK, a sports media firm set up by the King of Bahrain's son, said it had dropped Kinahan as an adviser.

And just two weeks after his video praising Kinahan, Fury's US promoter Bob Arum claimed the boxer had terminated his professional relationship with the Irishman.

However Arum added that Fury "loves, admires and respects" Kinahan.

The deal between Fury and Joshua was later scrapped after a ruling meant Fury had to face US boxer Deontay Wilder.

'Dangerous' Kinahan brings 'terror' to boxing

Ireland's former boxing world champion Barry McGuigan has spoken publicly of his serious concerns about Kinahan's role in the sport.

McGuigan branded Kinahan a "dangerous man" whose role in boxing had brought an "element of terror" to the sport.

He told a BBC Panorama documentary last year: "There is no doubt that there is an intimidation effect, there is no question about that.

"If we were to believe what we believe, this is a very dangerous man.

"There's an element of fear and terror around that name.

"Someone has got to look out for this sport. They really need to look at this situation very carefully, because it's bloody dangerous."

After the programme aired, the BBC said a Panorama team had been threatened from unnamed criminal elements in Northern Ireland in relation to the programme.

Kinahan denies criminal gang links

Following the Panorama programme, Kinahan issued a statement insisting he was not linked to a criminal gang.

He also said he was still organising "record-breaking world title fights" despite claims from broadcasters and boxing promoters that they are not dealing with him.

"I can't be any clearer on the fundamental slur - I am not a part of a criminal gang or any conspiracy," he told TalkSport.

"I have no convictions. None. Not just in Ireland but anywhere in the world."

Fury pictured with Kinahan in Dubai as boxing chief offers support

In February this year, Fury was pictured with his arm draped around a smiling Kinahan in Dubai.

A month later, World Boxing Council president Mauricio Sulaiman offered his support to Kinahan after meeting the Irishman.

Writing an opinion piece for The Herald of Mexico, Sulaiman said Kinahan had faced "prejudice" after being "labelled as a person linked to criminal groups".

He added: "I am nobody to judge any person, and that has been the policy of our organisation, to combat all types of discrimination and abuse of power, before any person and group."

Kinahan 'sources large quantities of cocaine from South America'

On Tuesday, the US government announced a $5m (£3.8m) reward for information leading to the arrest or conviction of Daniel Kinahan, his father Christy and brother Christopher Jnr.

The US treasury department described the Kinahan crime gang as a "significant transnational criminal organisation".

It said: "Each member of the KOCG (Kinahan Organised Crime Group) reports to Daniel Kinahan, who is believed to run the day-to-day operations of the organisation."

Kinahan has instructed members of the Kinahan crime group to send money to people serving prison sentences including individuals convicted of murder and attempted murder, according to the US treasury department.

Kinahan also "sources large quantities of cocaine from South America" and "plays an integral part in organising the supply of drugs in Ireland, and is attempting to facilitate the importation of cocaine into the United Kingdom," it added.

Some of the biggest figures in boxing - including Fury - have now been urged to cut ties with Kinahan.

Irish police commissioner Drew Harris said: "If you deal with these individuals who have been sanctioned, or these entities who are being sanctioned, you are involved in a criminal network.

"I'd ask them to look to their own business, at the probity of their own business and the relationship with their fans and, really, is this something they want to be involved with in terms of their legitimate business. I think the answer to that is a resounding no."