SHANGHAI Mayor Yang Xiong presented the Honorary Citizenship of Shanghai certificate to Joan Clos, under-secretary general of the United Nations and the executive director of the UN Human Settlements Program (UN Habitat), in a meeting on Monday.

Yang said Clos is an old friend of Shanghai people and played a key role in establishing sister city relationship between Shanghai and Barcelona when he was the mayor of the Spanish city. After taking his UN jobs, Clos continued cooperation with China and Shanghai and supported Shanghai's initiative to hold World Cities Day during the Expo 2010.

He noted that the UN General Assembly passed a resolution last year to designate October 31 as World Cities Day.