A former state president of Jamiat Ulema-e-Hindi and member of the All India Muslim Personal Law Board, Qasmi had won the Kishanganj seat for the first time in 2009 Lok Sabha polls and went on to retain the seat five years later. He was 76.
Other Congress leaders joined Gandhi in mourning the death of the leader.
Congress leader in the Lok Sabha Mallikarjun Kharge said the country has lost a learned leader. Qasmi always espoused and fought to preserve secular values, he added.
"I am deeply saddened by the demise of Mohammad Asrarul Haque, a senior Congressman and a popular leader from Kishanganj, Bihar, from where he was elected as Lok Sabha member twice. He was instrumental in setting up Aligarh Muslim University in his constituency," said Leader of Opposition in the Rajya Sabha Ghulam Nabi Azad.
Congress' chief spokesperson Randeep Surjewal also expressed his condolences on the passing away of Qasmi.
"My thoughts and prayers are with his family, friends and followers and to the people of Kishanganj and beyond," he said.
(With inputs from agencies.)