A manhunt has been launched to find a notorious people smuggler known as "Scorpion".
Authorities are looking for Barzan Kamal Majeed, 36, who is nicknamed after his WhatsApp avatar.
An investigation found migrants stopped by immigration officers had his number saved in their phones under the name “Scorpion.”
Last month in Bruges, Majeed, formerly from Nottingham, was sentenced to 10 years in prison and fined €968,000 (£853,000) for people smuggling offences.
The Belgian prosecution came after a joint investigation involving the National Crime Agency (NCA), Belgian, and French law enforcement revealed an organised crime gang used small boats, lorries and shipping containers to help people cross.
The investigation included 31 attempts to smuggle migrants into the UK between July 2018 and November 2019, with many of the migrants stopped having Majeed’s number.
His fellow crime group member Nzar Jabar Mohamad, 35, was sentenced in the UK last year.
Mohamed admitted to attempting to bring 21 migrants to the UK using lorries and small boats and was jailed for 10 years at Hull Crown Court.
The NCA has launched an investigation to find Majeed, with a spokesperson saying they strongly suspect he is currently in Northern Iraq after being deported from the UK in 2015.
The spokesperson said: "Mohamad was essentially the UK leg of the gang and Majeed was at the other end operating in Belgium and on the continent.”
The UK arrest warrant has been published because of Majeed's historic connections to Nottingham but the crimes he has been prosecuted for have all been in Belgium.
It comes as Rishi Sunak vowed to “grip this challenge of illegal migration” by working with European nations.
The prime minister met Emmanuel Macron for the first time as UK leader at the Cop27 climate conference in Egypt.
The government later said a new agreement between the UK and France, understood to be worth about £80 million, was in its final stages.
Meanwhile, home secretary Suella Braverman pledged to speed up the asylum system with a nationwide roll-out of a trial tested in Leeds to help streamline the application process.
She is under pressure for her handling of severe overcrowding at the Manston migrant processing centre, as well as questions about her own efforts to procure hotel accommodation for those seeking asylum in the UK.
Business secretary Grant Shapps described how the site in Kent was “tipping into becoming an unofficial detention centre” when he briefly held the post of home secretary.
Immigration minister Robert Jenrick later told the Commons there had been a “significant reduction” in the number of people at the facility, which was back below its maximum capacity of 1,600 after more than 2,300 migrants were moved to other accommodation.
In total, 39,913 people have crossed the Channel into the UK so far this year.