Government officials are upset about material insulting to Prime Minister Manmohan Singh, ruling Congress party leader Sonia Gandhi and major religious figures. Some illustrations have shown Singh and Gandhi in compromising positions and pigs running through Mecca, Islam's holiest city.

On Friday, the federal government told a New Delhi court that there was sufficient material to proceed against 21 social networking sites for offenses of "promoting enmity between classes and causing prejudice to national integration," according to the Press Trust of India news agency.

The cases, which PTI said name companies including Google, Facebook, Yahoo and Microsoft, represent a new risk of doing business in the nation of more than 1 billion people, which is looking to technology to boost its economy and standard of living. The dispute highlights India's difficulty in balancing the Internet culture of freewheeling discourse with its homegrown religious and political sensitivities.

Convictions could bring fines and up to five years' imprisonment, through prosecutors have named only the companies involved rather than any executives. Metropolitan Magistrate Sudesh Kumar on Friday asked India's External Affairs Ministry to serve summons to officials of foreign-based companies for court appearances March 13.

In December, Telecommunications Minister Kapil Sibal said he had spoken repeatedly with officials from major Internet companies over the past three months and asked them to come up with a voluntary framework to keep offensive material off the Internet. He said that the companies told him there was nothing they could do.

There was no immediate comment by the networking sites after Friday's court proceedings.

However, Facebook said last month that it would remove content that "is hateful, threatening, incites violence or contains nudity."

Google said in a December statement that it removes content that violates local law and its own standards.

"But when content is legal and doesn't violate our policies, we won't remove it just because it's controversial, as we believe that people's differing views, so long as they're legal, should be respected and protected," Google said in a statement in December.

Sibal had shown reporters Web illustrations showing Singh and Gandhi in compromising positions as well as a site showing pigs running through Islam's holy city of Mecca, a clear insult to Muslims.

Sibal said the Internet companies had told him that they were applying U.S. standards to their sites, and he objected, saying that they needed to be sensitive to Indian sensibilities.