The Anonymous hacking collective says it's brought down several UK government websites in protest at the country's treatment of Julian Assange.
The Ministry of Justice website has been intermittently down since last night, and the sites of Number 10 Downing Street, Department of Work and Pensions and the Home Office have also been affected.
Anonymous claimed responsibility on its Twitter feed for the DDoS attacks, which it's dubbed Operation Free Assange.
"Hey guise, some nasty anon cocks will be sucked by the UK government in coming days. Stay tuned," it says.
The Ministry of Justice has confirmed the attack, though it downplays its importance.
"This is a public information website and no sensitive data is held on it. No other Ministry of Justice systems have been affected," it says in a statement. "Measures put in place to keep the website running mean that some visitors may be unable to access the site intermittently."
Assange is currently in the Ecuadorian embassy, having been granted political asylum by the country. Police are camped out outside, ready to arrest him if he leaves the building.
He's trying to avoid extradition to Sweden over sex charges, but says he fears he'll be sent to the US for questioning over classified material published by WikiLeaks.