Some of the world's largest cities are improving their energy efficiency, a report said Thursday, while nations struggle to forge a global response to climate change.

Cities are taking action to reduce their carbon emissions and better manage their water strategy, said a report by the Carbon Disclosure Project (CDP), which runs a platform for companies and cities to measure, disclose, manage and share environmental information.

The 110-city report from the London-based organisation follows the G8 summit of world leaders hosted by Britain this week.

Los Angeles led the way, managing annual energy savings of $13 million (9.85 euros) -- largely by retro-fitting traffic signals and street lights --followed by Washington and Las Vegas with $6.3 million, the CDP found.

"Cities are hotbeds of innovation, and local governments have been quick to implement many new ways to combat and adapt to climate change and resource scarcity," said Conor Riffle, head of CDP's cities programme.

"These leading cities are enjoying multiple paybacks for their economies and communities. National governments should pay close attention."

Cities that took part in the study included Toyko, Seoul, Bangkok, Ho Chi Minh City, Jakarta, Singapore, Sydney, New York, Los Angeles, Mexico City, Sao Paulo, Buenos Aires, Johannesburg, Moscow, Paris and London.

The study found that the European cities surveyed produced $12,502 gross domestic product per metric tonne of carbon dioxide emissions, with South American cities producing $6,816, East Asian cities $5,831 and North American cities $5,550.

The report found that one out of every two actions cities take to reduce emissions are focused on efficiency.

It found that 62 percent of such actions had the potential to attract new business and investment.

Meanwhile it found that 55 percent of the cities studied were undertaking initiatives to reduce emissions that promote walking and cycling.

London Mayor Boris Johnson said: "Saving energy and using our resources more efficiently is absolutely vital to the sustainability, diversity and full recovery of this city's economy.

"The green sector represents a new area of expertise and innovation for London, providing jobs and attracting investment while significant carbon dioxide reductions can save businesses substantial sums, improve air quality and make the capital a better place to live and work."