The Serious Organised Crime Agency website has been taken temporarily offline after it was targeted by computer hackers.
The distributed denial of service (DDOS) attack - which involves web addresses being hit by a flood of visits - was carried out on Wednesday night, a Soca spokesman said.
The incident did "not pose any security risk to the organisation", he added.
DDOS attacks on the Soca website have previously been linked to the loose-knit international "hacktivist" group Anonymous.
Soca's website has been down since 10pm on Wednesday.