Scientists and officials stressed the importance of science and technology innovations in urban development at the World Expo's third theme forum, which opened in Wuxi, east China's Jiangsu Province, on Sunday.

City expansion had been achieved along with the burning of fossil energies like coal and oil during the past 200 years, but problems also arose including environmental pollution, energy shortages and global climate changes, said Minister of Science and Technology Wan Gang.

Renewable clean energy will replace traditional fossil energies and become the main energy form of future cities, he said.

The importance of science and technology innovations also lies in improving social welfare, as well as finding solutions to challenges such as food security, energy security and climate changes, said Supachai Panitchpakdi, the Secretary-general of the United Nations Conference on Trade and Development (UNCTAD).

With the theme "science & technology innovation and urban future", the two-day forum was co-organized by the Ministry of Science and Technology, the Executive Committee of Expo 2010 Shanghai China, the UNCTAD and the government of Wuxi.

Participants to the forum include Minister of Science and Technology Wan Gang, Nobel Laureate in Physics 1957 and Columbia University professor Lee Tsung-Dao, Nobel Laureate in Physiology or Medicine 2005 and clinical professor from the University of Western Australia Barry J. Marshall and China's agricultural scientist, widely known as the "Father of Hybrid Rice," Yuan Longping.

A total of 189 countries have sponsored pavilions at the six-month Shanghai World Expo, whose theme is "Better City, Better Life".