Britain is holding a Chinese national who is wanted in the United States on suspicion of conspiring to evade a goods export ban, London police said Saturday.
Cheng Sihai, 34, was arrested in February at London Heathrow Airport. The BBC said he faces allegations of conspiracy to export devices to Iran that could be used in uranium enrichment.
London's Metropolitan Police force said Cheng had already appeared at a court in the capital and was awaiting his next appearance.
"On February 7, Cheng Sihai, aged 34, was arrested by Met Police officers at Heathrow Airport in connection with alleged offences in the United States of conspiracy to evade the prohibition on the export of goods," a spokesman told AFP.
"Cheng Sihai, a Chinese national, was arrested on a provisional arrest warrant issued at Westminster Magistrates Court on February 7.
"He was taken into police custody and later appeared at Westminster Magistrates Court where he was remanded in custody. We await the date of his next court appearance."
The BBC said Shanghai-based Cheng is suspected of conspiring with an Iranian figure to supply US-made pressure transducers to Iran illegally via China.
Western powers and Israel suspect Iran is covertly pursuing a nuclear weapons capability alongside its civilian programme, charges adamantly denied by Tehran.
Iran's oil-reliant economy has struggled under US-led sanctions aimed at curtailing its nuclear ambitions.
The so-called P5 plus 1 group -- Britain, China, France, Russia and the United States plus Germany -- hopes to reach a final accord with Iran by July 20 which would lift all sanctions in exchange for Iran scaling back its programme to the point where it would be difficult if not impossible to develop nuclear weapons.