Three Intelligence Bureau officers from Delhi, learnt to be counter-terrorism experts on Indian Mujahideen and Jamaat-ul-Mujahideen Bangladesh, reached Ranchi late on Sunday to grill Intazar Ali, the Hindpiri resident arrested with live bombs and RDX-like explosives on a train last week.

The IB team, NIA sleuths who had arrived earlier and GRP personnel interrogated Ali (35) separately at an undisclosed location throughout Monday. It is not immediately clear if they found any other incriminating evidence against the man who practises medicine without licence and was nabbed from a compartment of the Burdwan-Hatia Passenger on August 20.

A high-level source said Ali still claims he was attending a training camp in Bengal's Jhalda, organised by an NGO run by a fourth-year MBBS student of RIMS who goes by the name of Dr Sarfaraz.

"Sarfaraz was quizzed by the agencies and asked to furnish registers and video of the camp. The putty-like substance suspected to be RDX has been sent for lab tests. The report is awaited," the source said.

Of the three mobile phone handsets confiscated from the accused, two have dual SIM facility. "Frequent calls were made to numbers in Delhi and Haryana. Ali has said he spoke to his brother-in-law in Haryana while he has a business in Delhi," the source added.

A policeman said IPC Sections 121A (waging war, attempting to wage war or abetting war against the nation) and 122 (collecting arms and ammunition with the intention to wage war against the nation) had been slapped on Ali.

As security agencies continue to probe where the bombs came from and why, family members of the accused have alleged violation of human rights.

"It has been four days (since Ali's arrest) and we haven't been allowed to see him even once. We respect the law. But, police can't treat my brother like a criminal until his crime is established," sister Shakila Khatoon complained on Monday.

She claimed they had been doing rounds of the GRP office at Ranchi station and Birsa Munda Central Jail in Hotwar, but in vain. "We are being harassed. We are spending sleepless nights. This is inhuman."

Officer-in-charge of Ranchi GRP R.K. Thakur said he was not authorised to speak.

DIG (railway) Priya Dubey said Ali was being quizzed in police custody and no one was allowed to see him. She did not answer how long the interrogation might continue and when Ali might be sent to jail.

Sources said Ali was handed over to GRP on August 21. The day after, he was produced in the railway court and taken in police remand for three days. The remand period will be over at noon on Tuesday.