* Govt official threatens legal action
* Google, Facebook say cooperating with Indian authorities
* Blocking access to websites a temporary fix, says expert (Adds details, reaction from Google, Facebook, quotes)
By Devidutta Tripathy and Annie Banerji
NEW DELHI, Aug 21 (Reuters) - India pressed social media websites including Facebook and Twitter on Tuesday to remove "inflammatory" content it said helped spread rumours that caused an exodus of migrants from some Indian cities last week.
The government said in a statement it had already blocked access to 245 web pages it said contained doctored videos and images, and the telecommunications secretary, R Chandrashekhar, threatened legal action against the websites if they did not fully comply with the requests to take down the offending pages.
Chandrashekhar told CNN-IBN television that Google and Facebook had largely complied with the government's requests while the response from Twitter had been "extremely poor", though he added that this "may be in part because they don't have an office in India".
Twitter was not immediately available for comment.
"A lot of inflammatory and harmful content/information has been found to be appearing on the social networking sites hosted outside the country," the government statement said.
The government met representatives of social media sites on Friday to push its case, it said.
The crackdown will likely rekindle a debate on freedom of speech and censorship of the Internet in the world's largest democracy.
Media group Reporters Without Borders said in March that India was increasing pressure on Internet service providers to supply users' personal data. Google says that between July and December 2011 there was a 49 percent jump in requests from India for content to be removed from its services, compared to the previous six-month period.
In a move that will likely add to their concerns, the government on Tuesday blocked a number of Twitter accounts that spoof the prime minister, local media reported.
"The government is for free information. There is no question of anything being censored here. But that does not mean there are not limitations," a senior official in the Ministry of Home Affairs said, adding that authorities were trying to identify those responsible for posting the inflammatory material.
Thousands of students and workers from India's northeast fled Mumbai, Bangalore and other cities last week fearing retaliation for violence against Muslims in the remote tea-growing state of Assam after threatening mobile phone text messages and website images sowed panic.
Clashes between indigenous people in Assam and Muslim settlers from neighbouring Bangladesh have killed nearly 80 people and displaced some 300,000 since July.
A cyber law expert said blocking web pages was "like putting a band-aid on a leaking roof". "It's a strategy that is doomed to failure from the word go. There are so many indirect ways to access the Net," said Pavan Duggal.
India has not released details of the blocked pages but said in a statement that "international social networking sites" had indicated that much of the content had been uploaded from neighbouring Pakistan, a long-time foe with which it has fought three wars.
An industry executive, who did not wish to be named, said companies "cannot share such information with the government".
"It's beyond their jurisdiction. This is an international issue, which the government is well aware of," said the executive.
Google and Facebook said they were cooperating with the government.
"We have received requests from Indian authorities and agencies and are working through those requests and responding to the agencies," Facebook said in a statement released by their Indian representatives.
Google has accepted the government's request to take down some content, while discussions are continuing on other requests, said a source with knowledge of the developments.
"We understand the gravity of the situation, strongly condemn acts of violence and continue to work closely with relevant authorities," Google spokeswoman Paroma Roy Chowdhury said in a statement.
Media reports said many of those panicked by the fear-mongering text messages and Internet postings have begun returning home this week. (Additional reporting By Ross Colvin and Satarupa Bhattacharjya in New Delhi and Harichandan Arakali in Bangalore; Writing by Ross Colvin; Editing by Alessandra Rizzo)