India has demanded social networking websites take down provocative messages and blocked some online content after anonymous threats sparked an exodus of migrants from southern cities.
Tens of thousands of workers and students from the remote northeast region returned home last week from Bangalore, Mumbai and other cities fearing attacks from Muslims in reprisal for recent ethnic clashes in the state of Assam.
The Indian government has said many of the Internet posts, fake video clips and phone messages spreading rumours of plans to target migrants were sent from arch-rival Pakistan.
The Ministry of Communications said late Monday that an order had been issued on August 17 but that "such inflammatory and harmful content continued to appear on the social networking sites".
It added the government was meeting with representatives of the sites to curb the content, and it stressed that "a lot more and quicker action is expected from them to address such a sensitive issue".
Google issued a statement on Tuesday saying any content intended to incite violence was already prohibited on its products, including YouTube videos.
"We understand the gravity of the situation... and continue to work closely with relevant authorities," it said in response to the government's demands.
Officials declined to name which other sites were affected, while Twitter and Facebook were not immediately available for comment.
The government also said 245 web pages had been blocked, declining to give further details.
Asked whether social networking sites were being used to whip up ethnic tension, Home Minister Sushil Kumar Shinde told reporters: "We have got sufficient evidence. The whole process is in investigation mode."
Local media reports estimated that over 35,000 people fled cities including Bangalore and Mumbai over the last week, packing special trains arranged to carry panicked students and workers back to the northeast.
Weeks of clashes in Assam between members of the Bodo tribal community and Muslims have claimed at least 80 lives and displaced more than 400,000 people.
The government says it is willing to share proof that much of the inflammatory Internet activity originated from Muslim-majority Pakistan.
Bulk text messages have been temporarily banned in India to halt the spread of threats and rumours of reprisals.