The shadowy online hackers group Anonymous blocked access to the websites of the Mexican Senate and the Interior Ministry Friday to protest a proposed law to fine people who violate copyright online.

The proposal, from conservative senator Federico Doring, is widely seen as the Mexican version of SOPA -- the US Senate and the Stop Online Piracy Act that Wikipedia and other Web giants have denounced as a threat to Internet freedom.

Anonymous announced the attacks on its Spanish Twitter account Friday.

Interior Secretary Alejandro Poire later told a news conference that the ministry's site had been blocked for around five minutes in late morning.

The site had not been compromised and officials were investigating, Poire said.

Doring said on his Twitter account that Anonymous had a right to show it was against his proposal but did not have a right to attack web pages.

He insisted that the proposal "does not contemplate any criminal punishment" and would not sanction users of social networks because they do not make profits.