Imtiaz, a resident of Ranchi, was arrested from Patna railway junction after a bomb exploded on platform number 10 Sunday morning, ahead of Bharatiya Janata Party (BJP) prime ministerial candidate Narendra Modi's rally here.
A court of the railway magistrate here sent Imtiaz to seven days judicial custody.
"He was produced before the court of railway magistrate here late Monday night and sent to high security Beur jail under judicial custody," said Superintendent of Railway Police Upendra Kumar Singh.
Patna Senior Superintendent of Police Manu Maharaj said two separate FIRs have been lodged with the government railway police and Gandhi Maidan police stations. Six of the seven blasts took place in and around the rally venue while one blast took place at the railway station.
Additional Director General (Special Branch) Rajesh Chandra said Imtiaz, the main accused caught with bombs at the Patna junction when he tried to flee after the first blast, was interrogated and confessed to his involvement.
"Imtiaz told police that a group of six people had been divided into three groups with specific assignments to carry out the blasts," Chandra said.
Maharaj said that Patna police will take Imtiaz in police custody in a day or two.
Six people were killed and 83 were injured in seven bomb blasts in Patna. The first of the blasts ripped through a toilet at around 10 a.m. at the railway station in the heart of the city, killing one person and wounding another.
After an hour, by which time Modi had reached Patna but not the rally ground, four explosions took place inside the Gandhi Maidan, and two around it that caused a lot of panic.
The Patna railway station is located two-three kilometres from the Gandhi Maidan.