The group has claimed to have broken into the telecom service provider's website using the Distributed Denial of Service (DDoS) mode on Wednesday. Anonymous is notorious for its attack on various government websites across the world.
The MTNL website was down for several hours in the late afternoon on many networks, solidifying the suspicion on such an attack. MTNL operates in Delhi and Mumbai.
Recently, Anonymous resolved against the decision by the Department of Telecom (DoT) to block all file-sharing websites, as against the court order to block only a few of them. "The Department of Telecom has ordered all internet service providers to block all file sharing websites, it's time for you to stand up and show that the corrupt government cannot stop you!" it has said on its website.
It has called for non-violent protests across the country on June 9 to voice against 'Internet censorship'.
The group had earlier targeted some government websites as well as those of corporates and political parties, which they accused of supporting the ban.