China's two mega-cities rank low among 40 metropolitan centers worldwide for global competitiveness, says a report by the Shanghai Academy of Social Sciences.

The report released on Wednesday evaluated 40 cities' for their response to global competition. Tokyo, London and Paris were ranked the top three, while Shanghai sits at the 21st and Beijing at 31st.

Six factors were listed as indications of competitiveness, including urban economy, cultural restoration, environment and ecosystem.

In terms of environment and ecosystem, Beijing and Shanghai both scored in the bottom five positions.

Beijing, the country's capital, ranked 39th, and was said to be "unfavorable for human living", according to the report.

Moscow sits at the bottom place for its toughest environmental conditions for living.

"This is mainly blamed on Moscow's geographic location and unique weather," said Su Ning, associate research fellow of the World Economy Research Institute of Shanghai Academy of Social Sciences, who participated in drafting the report.