Britain's Serious and Organized Crime Agency says its website has been taken down following a denial-of-service attack.
A spokesman says the site was taken down late Wednesday to "to limit the disruption on other clients of our hosting provider."
Denial-of-service attacks work by flooding a website with bogus traffic, effectively making it unreachable. Large attacks can also jam other websites hosted by the same provider.
Such attacks are easy to launch and generally do little lasting damage. The spokesman said Thursday that "we have had one or two before."
He spoke anonymously in line with department policy.