UNB, Dhaka :Environment activists on Saturday demanded the authorities concerned cancel the leases of lands on all riverbanks, including that of the Buriganga.They also demanded the removal of Bangladesh Inland Water Transports Authority (BIWTA) chairman for leasing out riverbanks in violation of a High Court order.The demands came at a press conference organised by nine environment and civic rights bodies including Nou, Sarak, Raill Khat Rokkha Jatiya Committee (national committee to protect river, road and rail sector) at the Jatiya Press Club. Speaking on behalf of the organizations, Ashish Kumar Dey, convener of the national committee, alleged that the BIWTA chairman has opened two vocational institutions in Barisal and Madaripur without taking any approval from the government.