Guwahati, May 24 : Pro-Khalistan leader and 'Waris Punjab De' chief Amritpal Singh was interrogated by the National Security Agency (NSA) officers in Assam's Dibrugarh jail. Singh has been lodged in the Dibrugarh jail since April 23 after he was taken into police custody from Moga's Rode village in Punjab. According to police sources, the NSA officers reached Dibrugarh on Tuesday and interrogated Singh for more than two hours. Meanwhile, the other nine associates of Singh, who are also lodged in the Dibrugarh jail, were also questioned by the NSA officers. A senior police officer on Wednesday said Singh was interrogated separately. Later, his aides were quizzed. Lat week, parents of Amritpal Singh - Tarsen Singh and Balwinder Kaur - met him in the jail. Earlier on May 4, Kiranpal Kaur, wife of Amritpal Singh, also met him in the prison. Kiranpal was accompanied by family members of another inmate and Amritpal's aide Daljit Singh Kalsi. Nine other associates of Amritpal Singh, including his close aide Papalpreet and uncle Harjit Singh, have been lodged in Dibrugarh jail since March. /IANS