Washington  - The United States congratulated the city of Rio de Janeiro for prevailing Friday in the tight competition to host the 2016 Summer Olympics.

"Congratulations, Rio," State Department spokesman Ian Kelly said. "I think it's great that South America will have its first Olympics."

US officials have expressed disappointment that Chicago's bid failed at the International Olympic Committee vote in Copenhagen despite intense last-minute lobbying effort from President Barack Obama and First Lady Michelle.

Chicago was a heavy favourite in the competition that also included Madrid and Tokyo, so its defeat in the first round of voting came as a surprise.

Kelly rejected the notion that tougher rules for travelling to the United States enacted after the September 11, 2001 terrorist attacks made it harder for US cities to make the case with the IOC.

"The image may have had something to do with it, yes, but I don't think that's the reality," Kelly said. "There are other factors, here, too. I mean, South America's never hosted an Olympics."

Obama made a quick trip to Copenhagen to boost Chicago, arriving Friday morning to shake some hands before returning quickly to Washington.

The head of the US Travel Association, Roger Dow, said there were members of the IOC who cited concerns about the difficulties of visiting the United States in the post-9/11 era and that the government needed to reform visa and security procedures.

"It's clear the United States still has a lot of work to do to restore its place as a premier travel destination," Dow said.  dpa