Pro-Khalistani leader Amritpal Singh, who is lodged in Assam's Dibrugarh jail, was interrogated by Intelligence Bureau (IB) officers on Tuesday, police sources said here.

The Waris Punjab De (WPD) chief has been kept in a separate cell. As per jail sources, he was not allowed to meet other members of the outfit, including his close aide Papalpreet Singh.

Nine associates of Amritpal were lodged at Dibrugarh Central Jail before he was brought there on Sunday.

A source in Dibrugarh jail revealed that IB officers went inside the prison this morning and that the interrogation of Waris Punjab De chief is underway.

Assam police is tight-lipped on the development.

Prasant Kumar Bhuyan, the Inspector General (Law and Order) of the Assam Police, told IANS, "All central investigation agencies, including IB and RAW, have officers posted in the state. Hence, it is not necessary that somebody from the national capital has to come to interrogate an inmate."

He, however, refused to comment on Amritpal's questioning.