Malicious software has been discovered in some computers belonging to the International Atomic Energy Agency (IAEA), according to new reports.
The agency is an international organisation designed to promote the use of peaceful nuclear energy, and discourage nuclear arms proliferation. The compromised computers were part of a network in its headquarters in Vienna.
"Data from a number of Vienna International Centre visitors' USB drives is believed to have been compromised," said spokesperson Serge Gas. However, the IAEA "does not believe that the USB devices themselves were infected or that they could spread the malware further. No data from the IAEA network has been affected."
He added that all necessary measures were being taken.
The IAEA carries out many politically sensitive tasks, foremost among them being its monitoring of Iran's contentious nuclear programme. For years, Israel, the US and other Western nations have accused Iran of secretly trying to develop nuclear weapons, a charge Tehran strongly denies.
Recently, Iran has become much more cooperative over the future of its nuclear programme, with talks held in Geneva on 15-16 October, and attended by the UN permanent members, the US, Russia, China, UK and France - plus Germany.
Hopes have been high, with Iran's Deputy Foreign Minister Abbas Araqchi hinting that "perhaps within three months or six months we can reach a conclusion."
This isn't the first time the agency has struggled with security breaches. Last November, the IAEA was the target of anti-Israeli hackers who posted the details of 100 nuclear experts on its website.
The reports come after a number of reports of high-profile hacking campaigns by the Tailored Access Operations (TAO) branch of the American National Security Agency (NSA), including computers belonging to the Presidents of Mexico and Brazil. Other networks compromised by the agency include the private residence of the President of France, the French embassy in Washington, DC, and France's UN mission in New York.
While there is no evidence to suggest that the NSA was involved in the IAEA breach, this latest disclosure seems to fit the profile of these similar attacks. However, fingers have also been pointed at Iranian hackers, whose capabilities have also hit the headlines in recent weeks.
The IAEA gave no indication of who it thought to be behind the attacks.