Vancouver Mayor Gregor Robertson has trashed the Canadian government's record on climate change in front of a distinguished audience at the U.S. State Department.

He is the only Canadian mayor invited to the "Our Cities, Our Climate" summit in Washington, D.C.

His comments came during a conference on green cities, organized by former New York mayor and current UN climate envoy Michael Bloomberg and attended by top officials from the department.

Robertson says Canada is an embarrassing laggard on climate change under the Harper government and hopes the Oct. 19 election produces a government that plays a more constructive role. 

His comments came at the end of a formal luncheon, in a panel discussion featuring three mayors — Robertson, and peers from Japan and Nigeria.

The Vancouver mayor met Secretary of State John Kerry, who delivered opening remarks at the event, although he left before the post-luncheon panel discussion started. 

"Mayors also have economic incentives to act, because people want to live in cities with clean air. And where people want to live, businesses want to invest. The more cities can attract talented and hard-working people, the more their economies will grow," Kerry and Bloomberg said in a joint statement. 

In an interview later, Robertson said he keeps hearing questions about Canada's climate record from people in Washington and during a recent visit to the Vatican.

American officials did not comment on Canadian domestic policy. They did, however, arrange media interviews with the visiting mayors. Robertson says he was invited to the summit several weeks ago.

Robertson was also the only Canadian mayor who met with Pope Francis at the Vatican to discuss the role cities can play in addressing climate change, sustainability, and poverty.

With files from CBC