India, with the world's third largest number of Facebook users, is clamping down on social media after recent posting of inflammatory videos on Web sites.

But the United States urged New Delhi to find the right balance between freedom of speech and the need to maintain law and order, a report by The Times of India said.

The government's move to block sites it deems unacceptable comes after doctored videos showing apparent violence against Muslims in Assam created violent panic.

While officials say they believe the videos originated on Pakistani blogs, the issue highlighted the uneasy relationship between freedom of speech on the Internet and the government's need to damp down inter-ethnic tensions.

Union Home Secretary R.K. Singh said New Delhi will be raising the issue with Pakistani officials.

"I am sure they (Pakistan) will deny it but we have fairly accurate technical evidence to show that the images originated and were circulated from their territory," he said.

Last week Indian federal and state ministers as well as police authorities watched closely as Assamese Muslims living and working in Bangalore engulfed the train station seeking train ticket home after rumors of the Web site information swept through their community.

Rail authorities and train companies in Bangalore, in the southwest state of Karnataka, put on extra trains to Assam in the northeast to cope with the influx of people who said they feared an outbreak of ethnic violence.

Twitter promised to cooperate with the government after the Prime Minister's Office complained to it about objectionable content on six accounts resembling the PMO's official account, a Press Trust of India report said.

Twitter said it was "actively reviewing" the request and will seek information from the Ministry of Communication and IT "to locate the unlawful content and the specific unlawful tweet," the PTI report said.

Facebook said it will comply with requests from Indian authorities but only where posts broke its existing rules that apply in all countries, a report by the BBC said.

"We have received requests from Indian authorities and agencies and are working through those requests and responding to the agencies," Facebook said. "Content or individuals can be removed from Facebook for a variety of reasons including issuing direct calls for violence or perpetuating hate speech."

At stake for many Internet service providers, site developers and proxy servers is a slice of one of the world's potentially most lucrative advertising markets.

A report by Businessweek in May said India will have more users of Facebook -- which opened an office in India in 2010 -- than any other country by 2015.

India has around 46,300,000 Facebook users,Socialbakers, a social media analytics firm in London, says. This makes India the third-biggest Facebook market behind second-place Brazil with just more than 48 million users and first-place United States with nearly 157 million.

The growth of users in India is around 22 percent a month and will match the United States by the end of 2014, each having around 175 million users, Socialbakers said.

However, the United States has voiced concern that India may overstep a censorship mark in its attempt to stamp out offensive Web sites.

State Department spokeswoman Victoria Nuland said Washington has been monitoring the situation of Assamese Indians flooding back to Assam from southern India because of concerns about their personal safety.

The U.S. government is "going to obviously watch and see how that process goes forward."

"We are always on the side of full freedom of the Internet," Nuland said in a report by The Times of India.

"But as the Indian government continues to investigate these instances and preserve security, we also always urge the government to maintain its own commitment to human rights, fundamental freedoms, rule of law."

Nuland also said the U.S. government maintained "open lines to our own companies in India, as we do around the world, and we are obviously open to consultation with them if they need it from us."

The weight of the law may be against most of Internet intermediaries, Pranesh Prakash, a lawyer at the Bangalore-based Center for Internet and Society, said.

"The rules are very onerous on intermediaries, since they require them to act within 36 hours to disable access to any information that they receive a complaint about," Prakash wrote in an article The Indian Express newspaper in May 2011.

Any "affected person" according to technology laws can complain about issues including defamation, blasphemy, trademark infringement, threatening the integrity of India, disparaging speech or the blanket "in violation of any law."

It isn't mandatory to give the violator an opportunity to be heard before taking down their content.

"Since intermediaries would lose protection from the law if they didn't take down content, they have no incentives to uphold freedom of speech," Prakash said.

"They instead have been provided incentives to take down all content about which they receive complaints without a considered evaluation of the content."