The protests, , follow a court order in March directed at ISPs, meant to prevent a newly released local movie from being offered in a pirated version online. Some ISPs went ahead and blocked some file-sharing sites altogether, rather than the offending URLs.

One such ISP, Reliance Communications, found its service was with last week, redirecting its users from sites like Facebook and Twitter to a protest page, according to reports from users. The hackers also claimed to have attacked the website and servers of Reliance, and claimed to have got access to a large list of URLs blocked by the company.

Reliance Communications said on Monday it had thoroughly investigated the matter and all its servers and websites are intact. "We have required preventive measures and strongest possible IT security layers in place to tackle any unwarranted intrusions," the company said in a statement. "Despite repeated attempts by hackers, our servers could not be hacked."

The hackers also claimed to have attacked websites of the Bharatiya Janata Party, the main opposition party in the country, after having previously launched DDoS (distributed denial of service) attacks on various websites including that of the Indian central bank, Reserve Bank of India.

Anonymous was active in India last year, when it attacked the website of the Indian army. It quickly and kept a low profile after drawing protests from some of its own members.