LONDON (Reuters) - Cyber attackers targeted British sport's anti-doping agency over the weekend without gaining access to any data, it said in a statement on Monday.
London-based UK Anti-Doping (UKAD) holds the test details and medical records of thousands of athletes, ranging from soccer players to high-profile Olympic medalists.
"Over the weekend UK Anti-Doping was made aware of a cyber attack affecting our systems. We can confirm that no data has been lost or compromised," the statement said.
"We took the necessary steps to investigate and resolve the situation. No core activity, including our testing program, has been impacted.
"We are satisfied that we have appropriate levels of cyber security in place, and we continually review our systems and measures to ensure they are of a very high standard," the agency added.
UKAD did not say where the attack was suspected to have originated or who might be behind it.
The Independent newspaper reported that staff had been sent home on Monday, with all of UKAD's electronic systems taken offline.
Cyber security researchers warned in January of indications that Russia-based hackers might be planning attacks against anti-doping and Olympic organizations following Russia's exclusion from last month's Pyeongchang Games.
Those Games in South Korea were subjected to a cyber attack during the opening ceremony but Russia dismissed allegations Russian hackers were involved.
A Russian hacking group known as Fancy Bear was blamed for an Olympics-related hack in 2016, when the World Anti-Doping Agency said the group was responsible for stealing and publishing confidential medical information about athletes.
Western governments and security experts have linked Fancy Bear, also known as APT28, to a Russian intelligence agency and have blamed it for operations including an attack on the Democratic National Committee ahead of the 2016 U.S. elections.
Moscow has repeatedly denied its involvement in these intrusions.
(Reporting by Alan Baldwin, editing by Pritha Sarkar)