Police in the Indian city of Bengaluru have arrested a technology executive in response to a UK public-service broadcaster's claim to have tracked down the person who operated the "most followed" pro-ISIL Twitter handle.

Bengaluru City Police announced on Saturday that the man identified by Channel 4 News as "Mehdi" and described by it as the operator of the now defunct @ShamiWitness account, had been detained.

He could be charged under sections of the Unlawful Activities Act and the Waging War Against the Country Act, media reports said earlier.

Mehdi Masroor Biswas will be jointly interrogated by the top three Indian intelligence agencies, the reports said.

Channel 4 News said it had traced to Bengaluru [formerly Bangalore], the Indian technology hub, the man who was seen across the world as an authority on ISIL, the group that controls large parts of Syria and Iraq.

@CPBlr - Bengaluru City Police arrest Mehdi Masroor Biswas owner of ShamiWitness twitter handle pic.twitter.com/DwKsnEBGy6 — BengaluruCityPolice (@BlrCityPolice) December 13, 2014

Channel 4 News said its investigation was based on its discovery that @ShamiWitness had used a personal email address, ElSaltador@gmail.com, to set up a personal Twitter account @ElSaltador.

Meanwhile, the Indian Express daily quoted Biswas as telling its corrrespondent "in a shaky voice from Bangalore, where he works for a giant food conglomerate, that his claims to Channel 4 about his support for ISIL and its executions and beheadings, was a ruse to get the reporter off his back".

Biswas told the newspaper: "I did tell Channel 4 that I believe beheading is part of Islam. It does not mean I believe in beheading. I never told them that I believe in beheading. That was misconstrued. They have made things complicated by airing the programme.

While speaking to Channel 4 News, Biswas had expressed apprehensions about his safety and feared imminent arrest .

'Family tense'

The Indian Express said Biswas is from the eastern Indian city of Kolkata and that his parents were tense at his home in the Kolkata suburb of Kaikhali on Friday.

His father practises homoeopathy after retirement, the report said, while his mother is a housewife who often visits her son in Bengaluru; she said she was with him just a few days earlier.

"You know being Muslim, we are easily identified as terrorists," his father told Indian Express .

The man behind influential pro-IS Twitter account Shami Witness tells #c4news he is "ready to surrender" - watch http://t.co/aQpsqQmBTs — Channel 4 News (@Channel4News) December 12, 2014

"The days are so hard now. But I can tell you that my son in innocent and has done nothing wrong. If he has landed in trouble, it is because some enemy is after him."

In the interview to Indian Express , Biswas said: "When Channel 4 called me first and asked if @ShamiWitness was my Twitter handle, I did not oppose it ... my outright rejection would not have convinced them. I therefore decided to admit that I was indeed @ShamiWitness in the hope that they would not air the programme.

"But I am telling you that I am not @ShamiWitness. Somebody must have hacked my email account which I used as ElSaltador@ gmail.com and used it to upload stuff. I have been framed. Someone must have planted this."

Speaking to Channel 4 News after Indian police said they were investigating him, Biswas said: "I haven't waged war against any allies of India. They might try to bring that charge. I haven't waged war against anybody.

"I just said stuff, people followed me, then I followed them back and then we talked. I only knew what the IS [ISIL] fighters or sympathisers said in public tweets."