The Indian government has threatened to block Twitter across the country if the microblogging site does not remove 28 hate pages within the next 12 hours.

The information ministry has issued Twitter with a deadline notice to remove "inflammatory and harmful" material that has allegedly triggered ethnic tensions against northeastern migrants living in southern cities.

Thousands of migrant students and workers have fled cities such as Mumbai and Bangalore in fear of retaliation for violence against Muslims in the northeastern state of Assam. Internet posts, phone text messages and fake video clips allegedly spread rumours that Muslims were poised to attack them.

"If Twitter fails to respond to our request, we will take appropriate action," senior home ministry official R K Singh was quoted as saying in the Times of India newspaper.

"We have asked the information technology ministry to serve them a notice."

Information technology minister Kapil Sibal said he was frustrated at the lack of response from US social networking sites.

"When we tell these sites to inquire about the identity (of people posting material), then they say we are out of your jurisdiction, our servers are outside and we are not under the obligation to disclose the identity.

"So this means it is a platform where anyone can do anything."

Twitter has promised to cooperate with the government by trying to locate the unlawful content.

"India is important to us and we would like to have clearer communication in these matters in the future," a Twitter spokesman said.

Facebook also vowed to remove any hate content. ""We have received requests from Indian authorities and agencies and are working through those requests and responding to the agencies," a spokesman said.

"We encourage people to continue to use our tools to report content they are concerned about so that we can investigate and take action."

The mass exodus of north-eastern migrants from southern cities follows a series of clashes in Assam between the Bodo tribe and Muslims, which have claimed at least 80 lives and displaced hundreds of thousands.