Speaking in Dublin, after the US government unveiled tough Russia-style sanctions against the gang, the US ambassador to Ireland Claire Cronin said the reward would be provided for “information leading to the financial disruption of the Kinahans, or the arrest or conviction” of Daniel Kinahan, his father Christopher Snr and brother Christopher Jnr.

Tackling the Kinahans “is an urgent priority for President Biden and the US government” Ms Cronin said.

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

“Today, the Kinihans join the ranks of the Camorra [Italian mafia organisation] and Japan’s yakuza”, said Gregory Gatjanis from the US dept of the treasury, which had earlier announced the sanctions.

Matt Horne from Britain’s NCA, which was involved in the international operation, said that today was “a huge blow to the Kinahans”.

“They thought they were untouchable, but we will explore every opportunity to disrupt their criminal activities. We will not stop here.”

The sanctions mean that money or assets the Kinahans have in the US, or in US banks, can be frozen, as well as any US-controlled properties, similar to the restrictions placed on Russian oligarchs in the wake of the invasion of Ukraine.

Their credit cards can be blocked and they cannot fly on US airlines.

As well as the three senior Kinahans, who are all now based in the United Arab Emirates, the sanctions also apply to associates Sean McGovern, Ian Dixon and Bernard Clancy, who are all based in Dubai, and John Morrissey who lives in Spain.

Two UAE-based companies, Hoopoe Sports and Ducashew General Trading, are sanctioned, as is Nero Drinks, which is based in Glasgow, and produces Nero Vodka.

The US says that John Morrissey owns or controls Nero Drinks, and “has given a significant portion of the business to Daniel Kinahan to compensate for loads of drugs seized by law enforcement”.

The Americans also said that Daniel Kinahan sources large quantities of cocaine in South America and attempts to import the drugs to the United Kingdom.

He fled Ireland after the infamous Regency Hotel shooting in 2016, when gunmen from the rival Hutch gang disguised as armed police attempted to murder him, killing an associate instead.

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

Daniel Kinahan lives in Dubai, where in recent years he has attempted to reposition himself as a boxing promoter, and has worked with Tyson Fury.

There is no suggestion that Fury was involved in any criminality.

Two weeks ago, Thomas “Bomber” Kavanagh, the “top man” in the UK for the Kinahans, was jailed for 21 years at Ipswich Crown Court.

The National Crime Agency (NCA) said that he masterminded a “commercial-scale” smuggling operation, and imported cocaine and cannabis worth more than £30m.

Two other men, Gary Vickery and Daniel Canning, also received lengthy prison terms.

Gardai (Irish police) are holding a news conference in Dublin later this morning, at which further details of the Irish and British involvement in the international operation against the Kinahans will be revealed.