Alejandro Cao de Benos, the founder of a pro-Pyongyang affinity organisation who bills himself as a "special delegate" for the government of North Korea, was arrested at Madrid's Atocha train station as he got off a train from Barcelona, a police spokesman told AFP

The 48-year-old Spaniard faces up to 20 years in jail if convicted, Spanish police said in a statement.

His extradition to the United States still must be approved by the Spanish government and courts, a process that can take months.

US federal prosecutors last year charged Cao de Benos and a British businessman, Christopher Emms, of recruiting American expert Virgil Griffith to illegally provide cryptocurrency and blockchain services to North Korea to help it evade sanctions.

The prosecutors accuse Cao de Benos and Emms of arranging for Griffith to travel to North Korea in April 2019 to their Pyongyang Blockchain and Cryptocurrency Conference where the American allegedly taught members of the secretive nation's government how to use cutting-edge techniques to launder money and circumvent sanctions.

Griffith, who holds a doctorate from the California Institute of Technology, was sentenced in April 2022 to 63 months in jail, and fined $100,000, after pleading guilty to a conspiracy charge.

Emms is still at large according to his description on the FBI's Most Wanted list.

The United States prohibits the export of goods, services or technology to North Korea without special permission from the Treasury Department's Office of Foreign Assets Control.

Cao de Benos founded the Korean Friendship Association in 2000, a club that is officially recognised by Pyongyang and claims on its website to have over 10,000 members around the world.

The former IT consultant has also coordinated visits by foreign journalists to North Korea and has acted as a middleman between the country's reclusive communist regime and foreign investors.

In 2016 he opened a small North Korean-themed bar, the Pyongyang Cafe, in the Mediterranean city of Tarragona.