A Chinese man wanted by US authorities for allegedly exporting banned uranium-enriching devices to Iran has been arrested in London.
Sihai Cheng is in police custody after being arrested on a provisional US warrant at Heathrow Airport in February, and appeared in court recently.
A judge will rule whether to deport him to the US in June.
The US indictment alleges that Shanghai-based Cheng conspired with an Iranian to illegally import US-made pressure transducers to Iran through China.
The devices can be used in gas centrifuges to produce weapons grade uranium. According to the indictment, the transducers have been photographed attached to gas centrifuge cascades at Iran's Natanz nuclear facility.
US prosecuters allege that Cheng began doing business with Tehran-based Seyed Abolfazl and Shahab Jamili and Iranian engineering company Nico Eng. Co. in 2005, and has sold Jamili thousands of Chinese-manufactured parts with nuclear applications.
By email, Jamili informed Cheng that the parts were in fact being bought by Iranian company Eyvaz Technic Manufacturing Co, which was in turn supplying the devices to the Iranian government.
Cheng subsequently sent parts directly to Eyvaz, which in 2009 enquired about the possibility of Cheng acquiring the pressure transducers.
Between April 2009 and January 2011 Cheng ordered more than 1,000 pressure transducers from Massachusetts company MSK Instruments Inc, with a value of more than $1.8 million.
Cheng warned Jamili of "critical control condition and boycott by USA government," and ordered the devices in batches of 30 to 100, the indictment alleges.
Western powers have accused Iran of attempting to develop a nuclear weapon under the cover of its nuclear energy programme, which Tehran strongly denies.
Sanctions imposed by the EU and US in 2012 have hit Iran's oil-based economy hard.
Britain, China, France, Russia and the United States plus Germany, which make up the so-called P5+1, hope to reach an agreement with Iran by 20 June, where in exchange for scaling back its nuclear programme, sanctions will be lifted.