Railway Minister Suresh Prabhu listed a series of environment-friendly initiatives undertaken by the Railway Ministry. (File Photo)

Railway Minister Suresh Prabhu on Sunday made a strong pitch for controlling human population to tackle environmental issues and to reduce the pressure on natural resources caused by growing demand."Unless, globally we accept the fact that population is a challenge, we will not be able to actually solve the big issues we face...the type of economic demands that these number of people are going to make out of the planet...if the population goes down, the demand will go down," he said.Mr Prabhu made the remarks at an event organised in New Delhi by India Eye International Human Rights Observer and UN Information Centre for India and Bhutan to mark World Environment Day on Sunday.Mr Prabhu noted that there are some countries and certain sections of societies including those in India which enjoy natural resources "disproportionate" to their numbers."But at the same time, we must address the (population) demand side issue," he said and called for dealing with environmental issues in a "collaborative and co-operative" manner.Mr Prabhu also listed a series of environment-friendly initiatives undertaken by the Railway Ministry including use of solar energy and steps taken to save water.The Minister also presented environmental activist Sunita Narain a lifetime achievement award at the event, which was also attended by renowned water conservationist Rajendra Singh, film directors Madhur Bhandarkar and Ashoke Pandit, Parmarth Niketan Ashram president Swami Chidanand Saraswati and others.