The FBI has arrested a British cybersecurity researcher credited with helping to stop the global WannaCry ransomware attack.
Marcus Hutchins was detained on Wednesday in Nevada, according to the US Marshals Service.
Thousands of hackers had descended on Las Vegas for the annual Black Hat and Def Con security conferences.
The security website Motherboard, which first reported the arrest, said Hutchins was initially held at the Henderson Detention Center in Nevada and then moved to another facility.
An FCO spokesman said: “We are in touch with local authorities in Las Vegas following reports of a British man being arrested.”
The malware researcher gained attention for detecting a “kill switch” that effectively disabled the WannaCry worm in May.
The attack struck the NHS and infected hundreds of thousands of computers worldwide, causing disruption at car factories, hospitals, shops and schools in more than 150 countries.
The software, called WannaCry or Wanna Decryptor, exploited a vulnerability in the Windows operating system.
It allowed the malware to automatically spread across networks, so it can quickly infect large numbers of machines at the same organisation.