The smuggler was based in Turkey and had links to the jihadist Islamic State, also known as ISIS, according to a US official who spoke on condition of anonymity. CNN first reported the incident.

Record numbers of migrants have crossed the US-Mexico border illegally since President Joe Biden, a Democrat, took office in 2021, including many from distant nations.

Republicans say Biden encouraged crossings by reversing tougher policies of former President Donald Trump, a Republican. The Biden administration argues that it has instituted more humane policies as migration has challenged countries across the Western Hemisphere.

Of the nearly two million migrants encountered at the US-Mexico border between October 2022 and July 2023, 216 were on US watchlists for potential links to terrorism, according to US government statistics.

US intelligence officials discovered a smuggling network to bring Uzbeks into the country and a smuggler with ties to a US-designated foreign terrorist organisation, White House National Security Council spokesman Adrienne Watson said in a statement.

US authorities have no indication that migrants aided by the smuggling network were tied to extremist groups or plotting terrorist attacks, Watson said.

Watson did not confirm links to the Islamic State specifically or that the smuggler was based in Turkey.

Migrants who “fit the profile” of those assisted by the smugglers are being placed in rapid deportation proceedings and “thoroughly vetted,” Watson said.

The US official said the Federal Bureau of Investigation is trying to locate about 15 of roughly 120 Uzbek migrants who entered the US through legal border crossings via the network.

An FBI spokesman said the agency “has not identified a specific terrorism plot associated with foreign nationals who recently entered the United States at the southern border,” and declined to comment on specifics.

US Customs and Border Protection encountered some 3,200 Uzbeks at US borders in fiscal year 2022, up from fewer than 700 a year earlier.