Federal government websites were hit by a cyberattack Wednesday and the hacking group Anonymous has claimed responsibility for the attack.

The websites for several federal departments -- including Weather.gc.ca, ServiceCanada.gc.ca and Parl.gc.ca -- went down around the lunch hour ET Wednesday.

Many federal employees also lost email service. Some sites, such as National Defence, remained online.

The sites appeared to go back online shortly before 3 p.m. ET.

Treasury Board President Tony Clement confirmed to reporters on Parliament Hill Wednesday afternoon that the shutdowns were caused by a denial of service cyberattack.

“I’ve just been through a briefing on it,” Clement said. “There has been an attack on Government of Canada servers.”

“We are working very diligently to restore services and to find out the origination of the attack,” he added.

“If Canadians have any issues and are being denied access to a GC account, they should phone 1-800-O-Canada,” Clement advised.

Clement could not say whether any data had been stolen or who might have directed the attack.

‘Anonymous’ video

A video released on YouTube claiming to be from the global hacking group Anonymous took responsibility for the attack. The video has not been independently verified by CTV News.

“We launched an attack against Canadian Senate and Government of Canada websites in protest against the recent passing of Bill C-51,” says the video’s narrator, whose voice has been disguised.

“(C-51) is a clear violation of the Universal Declaration of Human Rights as well as removing our legal protections that have stood enshrined in the Magna Carta for 800 years.”

The narrator criticizes Prime Minister Stephen Harper, calls for “revolution” and asks Canadians to “take to the streets and protest” on Saturday.

The video shows scenes from protests overseas and in Canada, including one that took place on Parliament Hill.

Bill C-51, the Anti-Terrorism Act, passed in the House of Commons in May and was rubber-stamped by the Senate on June 10.

The law broadens the powers of the Canadian Security Intelligence Service to investigate and thwart suspected terrorist plots.

Critics of the bill fear it will allow security officials to monitor legitimate activities online.

The bill was introduced by the Conservatives, supported by the Liberals and opposed by the NDP and Green Party.

No personal information compromised

Public Safety Minister Steven Blaney said Wednesday afternoon that “no personal information was compromised.”

Blaney also said that police are investigating and that there is “no excuse” for attacking “public property.”

“We are living in a democracy,” Blaney said. “There are many ways to express your views.”

Earlier warning

Wednesday’s blackouts come just a few days after House of Commons IT warned that its employees are "currently being targeted by several cyberattacks."

Two memos sent Friday IT staff said hackers were sending phishing emails that look like they come from official accounts, but instead are a technological ruse to trick recipients into giving up personal information.

Last summer, a phishing scam allowed hackers into the systems of the National Research Council, forcing the NRC to shut down its computer system and use a temporary network.

The federal government blamed China for that attack.

What is a DoS attack?

Toronto-based website security expert Claudiu Popa told CTV News Channel that a denial of service attack is the “low-hanging fruit” of cyberattacks.

“It’s a simple flooding of the website with a number of simulated connections, so you’re pretending to be connecting to the site not from one browser, but from a million,” he said. “They’re not designed to handle that kind of load.”

Popa said the websites that went down Wednesday “don’t contain sensitive information,” and so they are “protected less-so than ones that do have sensitive information.”

“Obviously there’s a bit of a reputational impact when they get taken down,” he added.