WASHINGTON: The United States' top climate official said there had been a "narrowing of differences" after a meeting of the world's 17 top polluters that are critical to reaching any international deal on curbing climate change.

Todd Stern, the US State Department's envoy on climate change, said Friday some "concrete initiatives" that could help broker a deal were considered during two days of talks by the climate officials in Washington.

"There was some narrowing of differences" Stern said, but did not offer specifics. The talks focussed on efforts to reduce greenhouse gases blamed for global warming, how to adapt to its consequences and encourage renewable technologies.

Stern's comments come ahead of a major week for climate negotiations. World leaders will discuss the topic at a United Nations summit in New York on Tuesday. Leaders of the Group of 20 (G20) bloc of wealthy and developing countries are also expected to discuss ways of financing climate initiatives during their two-day summit beginning Thursday in Pittsburgh, Pennsylvania.

All of the various talks are aimed at reaching a global climate treaty at a major UN-backed conference in Copenhagen in December.