India targets social media sites after Assam violence
Indian authorities have cracked down on social networking sites following unrest and an exodus of migrant workers fearing revenge attacks.
The government threatened legal action against the websites if they did not remove "inflammatory" content.
Facebook and Google have removed some material, but only in cases where it broke rules on hate speech and inciting violence.
The government said Twitter's response had been "extremely poor".
However, it acknowledged this "may be in part because they don't have an office in India".
Twitter could not be reached for comment on Wednesday.
Authorities claim that threatening messages and pictures - which they allege have mostly originated in Pakistan - have been sent over the web to migrant workers following clashes between tribes in the north-east Indian state of Assam last month.
Fearing more violence against ethnic minorities, thousands of people have fled the cities of Bangalore and Pune in recent days.
The government has said social networking sites were used for scaremongering.
Additionally, India's Telecommunications Secretary R Chandrashekhar said at least 245 web pages had been blocked in the country for hosting doctored videos and images.
However, the Indian Express newspaper disputed the motives of the web page blocks, suggesting an overzealous level of censorship.
In an article published on Wednesday, it said that only one-fifth of the sites involved contained any reference to "the people of the north-east or the recent violence in Assam".
Facebook has said it will comply with requests from Indian law enforcement, but stressed it was only in cases where posts broke its existing rules that apply in all countries.
"We have received requests from Indian authorities and agencies and are working through those requests and responding to the agencies," the site said.
"Content or individuals can be removed from Facebook for a variety of reasons including issuing direct calls for violence or perpetuating hate speech."
Spoof Twitter accounts
The Times of India reported that the government had also moved to block access to certain Twitter accounts that were spoofing the prime minister.
Six accounts - with names such as PM0India, Indian-pm and PMOIndiaa - were blocked on Tuesday. It is believed that local internet service providers were responsible for putting the block in place.
An official from the prime minister's office told the Times of India: "We are fine with parody, even though at times it is in bad taste, and there is criticism of the government.
"But we cannot allow anyone to misrepresent the PM's office and tweet nonsense from these accounts," he said.
The newspaper reported that Twitter had been contacted in June about the accounts, but had not responded.
The added government pressure on sites and internet service providers will fuel debate in the country over censorship issues.
It is an unwelcome distraction as India tries to position itself as a developing hub for hi-tech business and commerce in Asia.
Google has said that between July and December 2011 there was a 49% jump in requests from India for content to be removed from its services, compared with the previous six months.
In 2011, the government sought greater access to the tight security system used on Blackberry smartphones.