The accused, who had their faces muffled, were produced amidst tight security before District Judge Amar Nath during an in-camera proceeding.
According to the court sources, the NIA sought their custodial interrogation saying that they were required to be quizzed to unearth the conspiracy of ISIS to spread its reach in India.
The sources said that the probe agency informed the court that the accused were arrested for allegedly planning to carry out attacks ahead of the Republic Day.
The 12 accused produced before the court were Abdul Ahad, Imran, Mohd Afzal, Mohd Sharif, Mubabiir Mushtaq Sheikh, Mohd Alim, Syed Mujahid, Suhail Ahmed, Asif Ali, Njmul Huda, Mohd Obaidullah Khan and Mohd Hussain Khan, the sources said.
These arrested accused were allegedly regularly in touch with active members of IS in Syria through internet chatting via Skype and other social networking apps, they said.
Many of these accused were allegedly assigned the work of recruiting operatives for the terror group, the sources said, adding that the accused were arrested from various places, including Bangalore, Hyderabad, Mumbai and Aurangabad.
Two suspected terrorists -- Abu Anas and Nafees Khan, both aged 24 years -- were on Sunday remanded in the custody of the central terror probe agency by the court for 13 days on the allegations that they had Islamic State links.
NIA and other central agencies had arrested 14 people on Friday and Saturday for allegedly planning to carry out attacks ahead of the Republic Day.
They were arrested under several sections, those under Unlawful Activities (Prevention) Act.
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