Britain's Home Office said Sunday its website was temporarily unavailable overnight, and hackers are claiming responsibility for shutting it down.
The hackers also claim they attacked Britain's Ministry of Justice website Saturday night and warned of further attacks every Saturday to come on U.K. government websites.
The alleged hackers - who claim ties to Anonymous, the hacker collective - said on Twitter that they launched Saturday's denial-of-service attacks and brought down the websites to protest "proposed draconian surveillance measures," Britain's extradition policies and "derogation of civil liberties."
The authenticity of their claims could not be verified. Denial-of-service attacks - which flood websites with too much traffic - are relatively easy to pull off and generally do no lasting damage.
The Home Office confirmed that its site was temporarily inaccessible Saturday night, saying it is aware of reports that its website may have been the subject of "an online protest." It added that it will be monitoring the situation closely and declined to provide more details on what caused the site to choke.
The Home Office and Ministry of Justice websites were both operating normally Sunday morning.
From the official website of Citibank to Central Intelligence Agency's website, hackers have been directing their ire on various high-profile websites. Check out some websites brought down by hacking groups recently.