An IIT Guwahati student was arrested on Sunday under the Unlawful Activities (Prevention) Act, a stringent anti-terror law, a day after he was detained for alleged links with terror outfit ISIS.

This is the third arrest by the special task force (STF) of the Assam police since Wednesday.

The police said on Sunday that the accused, Tauseef Ali Farooqui, a 23-year-old B-Tech final year student, was arrested in the “IIT-Guwahati-ISIS case” under IPC Sections 120 (B), 121 (A), 123 along with Section 10 and 13 of the UA(P) Act.

After being detained by the police’s Special Task Force (STF) from Hajo in Kamrup district, about 35km from Guwahati, on Saturday, he was produced before the CJM court here on Sunday.

The court remanded Farooqui, who hails from Okhla in Delhi, to 10 days in police custody even though the police had sought 14 days custody. The police did not share details except that “further investigation is underway”.

However, Assam chief minister Himanta Biswa Sarma has said there could be another “radicalised” student at the IIT and efforts were on to “trace” him.

The IPC sections under which Farooqui has been booked deal with criminal conspiracy (120-B), conspiring to commit offences against the State (121 (A)) and concealing the existence of design/intent to facilitate design to wage war against the State (123) while the UAPA sections deals with penalty for being member of an unlawful association (10) and advocating, abetting, advising or inciting the commission of any unlawful activity (13).

An STF officer said on Saturday night that the IIT student, hailing from Delhi, was picked up from Hajo in Kamrup district around 7.30pm, hours after his purported three-page letter to “whomsoever it reaches”. The letter was released on social media platform LinkedIn in the afternoon where he purportedly stated he would “disassociate myself completely from the ... so-called Indian Constitution, its institution and so on”.

The police officer on Saturday said they visited the IIT campus in the afternoon.