Abdul Halim, a suspected member of the outlawed Students Islamic Movment of India (SIMI) arrested in the aftermath of the serial bombings in Ahmedabad, was on Monday remanded in 14 days' police custody.
Metropolitan Magistrate GM Patel sent Halim to police custody on an application by the crime branch of the city police.
Halim was arrested Sunday. He was the first to be arrested in connection with the 21 serial blasts that killed nearly 50 people and injured more than 200.
The crime branch has stated that Halim has been a prime mover behind terrorist activities in the country.
He was wanted in connection with the communal violence of 2002 and a case was registered against him in 2003-04. Police sources said Halim was not directly involved in the serial blasts though he could provide vital clues about the elusive killers.
Halim allegedly acted as an operator for a terror outfit and helped send men to Pakistan and Bangladesh for terrorist training, they said.
The police conducted raids in various parts of Ahmedabad and nearly 30 people have been taken into custody so far.
At least 50 people were killed and about 200 injured as 21 synchronised bombs rocked Ahmedabad on Saturday evening.