Mehdi Masoor Biswas, who police said was behind the @ShamiWitness Twitter handle, has cooperated with investigators since he was picked up from his one-room apartment in Bengaluru city on Saturday, the government said.
His account was disabled at that time and it was not clear how it became active again. Police said the account was part of their investigation but not under their control.
Security officials said @ShamiWitness had been reactivated to determine if Mehdi was a cheerleader or an online recruiter for Islamic State.
"Police are investigating if there are more people like Mehdi," said Hemant Nimbalkar, a joint commissioner of police in India's high-tech capital previously known as Bangalore.
Biswas told police that more than 60 percent of his Twitter followers were non-Muslims and the majority of his Muslim followers were from Western countries, particularly Britain, Home Minister Rajnath Singh told parliament.
Each day, Mehdi, 24, sent out hundreds of posts, applauding Islamic State's advances in Iraq and Syria and mocking its enemies, while working by day as a food company executive.
His interrogation had indicated that his activities were limited to posting and reposting of pro-ISIS material on his Twitter account and other social media sites, Singh said, adding that Mehdi had denied recruiting volunteers.
India has the world's third-largest Muslim population, but they have largely shunned Islamist causes. Police say only four Indians are known to have joined Islamic State fighters, and one had since returned and is in custody.
The clean-shaven Mehdi's role as a propagandist for the Middle Eastern group, revealed by Britain's Channel 4, has exposed India's vulnerabilities and its inability to keep track of people turning to the group's violent ideology.
Mehdi told police he started following developments in Syria, Iraq and Afghanistan while in college and had been active on social networking sites since 2009.
Originally using the name "El Saltador" he began sharing information about the war in Syria and gradually became an online voice with an apparently vast knowledge of the conflict, but always with a polite tone.
By the beginning of this year, he was cheering the successes of Islamic State and praising its fighters after their deaths. "You bros talked the talk, walked the walk," he wrote about Iftikhar Jaman, a British ISIS fighter killed in Syria a year ago.
© Thomson Reuters 2014
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