The world should work together in common cause for peace, justice, dignity and development, UN Secretary-General Ban Ki-moon said yesterday, in a message to mark the World Humanitarian Day.World Humanitarian Day is marked every year on August 19, in honour of aid workers who have lost their lives in the line of duty."We commemorate their sacrifice and reaffirm our commitment to the life-saving work that humanitarians carry out around the world, every day, often in difficult and dangerous circumstances where others cannot or do not want to go,” the UN boss said.This year’s commemoration marks the 10th anniversary of the attack on UN headquarters in Baghdad that killed Special Representative Sergio Vieira de Mello and 21 other United Nations colleagues and partners.That tragedy was among the inspirations for this Day."My word is ‘teamwork.’ In a time of global challenges, people and countries need to work together in common cause for peace, justice, dignity and development. That is the humanitarian spirit. That is the humanitarian imperative of the United Nations,” Ban said.Sergio was a vocal advocate of the values and mission of the United Nations.He is said to have touched the lives of all who met him, and helped millions of poor and vulnerable people in a life of service on several continents.His death was a great loss to the United Nations, the UN chief said, but his legacy has motivated many people to pursue humanitarian work.This year, the World Humanitarian Day campaign called on people to answer the question: What do you think the world needs more of? People were urged to go to www.worldhumanitarianday.org and mention in one word, what they think.