Websites run by the Canadian government were attacked on Wednesday, causing widespread service interruptions. The “Anonymous” hacker collective claimed responsibility for the attack, describing it as a protest against the recent passage of a controversial anti-terrorism bill, which the hackers denounced as “a clear violation of the universal declaration of human rights.”

Anonymous delivered its message by video, as is customary for its communiques:

The video calls for supporters to stage a protest on June 20th and to “disregard these laws, which are unjust, even illegal.”

The hackers appeared to threaten further mayhem by declaring, “the games have just begun,” on their YouTube channel and Twitter account, which listed government website targets with the declaration “Tango Down,” a phrase generally used by counterterrorist forces to indicate an enemy has been neutralized during combat operations.

The Global News reports that government officials have not yet definitively identified Anonymous as the source of the attack, which took down websites including “Canada.ca and the sites for Foreign Affairs, Transport Canada, Citizenship and Immigration and Justice Canada,” along with dozens of lesser departmental sites, and even “reportedly affected BlackBerrys and internal network services.”

The debate over Bill C-51 is similar in many ways to the arguments posed by American civil libertarians against broad-based surveillance programs and anti-terrorist legislation such as the Patriot Act. At the beginning of June, the Global News reported a letter from several traditionally conservative and libertarian Canadian organizations to Prime Minister Stephen Harper, asking him to kill the bill, which they said would “create a domestic spy agency designed to target all Canadians.”

The letter expressed fears that the bill would lead to the creation of “databases on all Canadians with no oversight,” disclosing sensitive personal information to a wide variety of government agencies. The letter says the bill threatens freedom of speech and the rule of law by allowing for “secret trials and for speech to be censored by removal from the Internet or by vague, and even unconstitutional ‘disruption’ measures that can be applied to Canadian website operators.” According to the letter, the bill would also unleash upon Canadians an army of “civil service bureaucrats operating covertly without oversight, regulation, or accountability.”

“Do you really want to live in a C-51 Canada that you don’t govern? We thought not. We don’t either. Kill Bill C-51,” the signatories urged, warning Harper that his Conservative Party could face severe electoral repercussions if it passed.

Normal service was reportedly restored to affected government websites after several hours. Last week, employees of the Canadian House of Commons were warned to be on guard against possible cyberattacks, including “suspicious emails from hackers looking for personal information,” as the National Observer reported.