LONDON -- Pro-Russia hackers have claimed responsibility for a cyber attack that crashed the British royal family's website over the weekend.

The website, royal.uk, went down for over an hour on Sunday morning due to a denial-of-service attack, a tactic for overwhelming a machine or network to make it unavailable, a royal source told ABC News.

The source said the website was not hacked because no access was gained to systems or content. It was unclear who was responsible fort the denial-of-service attack, according to the source.

There was no official comment on the matter from Buckingham Palace.

A pro-Russia hacktivist group that calls itself Killnet claimed to be behind what it described as an "attack on paedophiles," apparently referring to Britain's Prince Andrew, Duke of York, who was accused of sexually abusing an American woman when she was 17, claims the prince has denied.

Killnet has been active since at least 2022, around the time that Russia launched an invasion of neighboring Ukraine. The group has become known for its distributed denial-of-service (DDoS) attacks against countries supporting Ukraine in the ongoing war, especially NATO members, according to an analyst note released earlier this year by the Health Sector Cybersecurity Coordination Center within the U.S. Department of Health and Human Services.

"While KillNet's DDoS attacks usually do not cause major damage, they can cause service outages lasting several hours or even days," the note states. "Although KillNet's ties to official Russian government organizations such as the Russian Federal Security Service (FSB) or the Russian ForeignIntelligence Service (SVR) are unconfirmed, the group should be considered a threat to government and critical infrastructure organizations including healthcare."

Sunday's cyberattack came days after Britain's King Charles III voiced support for Ukraine during a speech at the French Senate in Paris. He referred to Russia's "military aggression" as "horrifying."

"Together, we are unwavering in our determination that Ukraine will triumph and our cherished freedoms will prevail," Charles said in his remarks on Sept. 21.

The British monarch has spoken out against Russia's war in Ukraine previously several times.