LONDON (Reuters) - Hackers attacked the website of Britain's Serious Organized Crime Agency (SOCA), a spokesman said on Thursday, the latest in a wave of assaults against high profile targets like NASA, the Vatican and multi-national companies.

The national police agency, often described as the British FBI, said it closed the website late on Wednesday after it came under attack from an unknown source.

Internet activist groups such as Anonymous, LulzSec and Antisec have previously been linked to attacks against bodies including the U.S. Senate, Sony and Visa.

A SOCA spokesman said that no confidential information had been lost during the incident, known as a distributed denial of service (DDoS) attack, where a website's host computers are bombarded with requests for information, making them crash.

"We elected to take our website offline at 10 p.m. last night. That action was taken to limit the impact of the DDoS attack on other clients hosted by our server," he said.

"The website contains only publicly available information and doesn't provide access to any operational material."

Visitors to SOCA's website were shown a page labeled "Network Error", with the message: "A communication error occurred: Connection refused". There was no immediate word on who was behind the attack.

The agency, which investigates serious crimes like people smuggling, drug trafficking and shootings, last month shut down 36 web domains being used to sell stolen credit card data.

It has been a victim of cyber attacks before. In February, members of Anonymous published a recording of a phone call between FBI agents and London detectives in which they talked about their plans to tackle hacking.

Cabinet Office minister Francis Maude warned this week that this summer's Olympic Games in London are also likely to come under cyber-attack.

(Reporting by Peter Griffiths)