UPDATE 1-Olympics-Madrid 2016 bid has most public support-report

* 93 percent of Spaniards back Madrid bid

* Public support is the weakest in Japan (adds Tokyo 2016 CEO comment paragraphs 10-11)

By Antonella Ciancio

MILAN, Sept 1 (Reuters) - Spaniards stand united behind Madrid's bid for the 2016 Olympic Games while Tokyo has the weakest public support among the four potential host cities, a global study showed on Tuesday.

Germany-based sponsoring consultancy Sport+Markt said 93 percent of Spanish respondents backed the Madrid bid, closely followed by Chicago and Rio de Janeiro.

The International Olympic Committee (IOC) will announce the 2016 Olympic host city on Oct. 2 in Copenhagen.

"The population's passion for a sports event is the key to its success," said Hartmut Zastrow, executive director at Sport+Markt.

Madrid, bidding for the second successive time, is banking on the legacy of the Barcelona 1992 Games and its Mediterranean climate to swing the vote but is widely seen as an outsider.

"The Spanish enthusiasm for Madrid's bid is very remarkable. Madrid's chances are said to be low as the Summer Games in 2012 in London are already on European soil," Zastrow added.

Tokyo, which topped the International Olympic Committee's (IOC) overall technical evaluation last June ahead of Madrid, ranks as the lowest bidder for local support.

Just 72 percent of 1,000 people interviewed across Japan judged its proposal "good or very good", the report said.

"The bid of Tokyo does not have enough support in its own country so far," Zastrow commented. "This weakens the Japanese bid immensely."

Ichiro Kono, chairman and chief executive of Tokyo 2016, was confident millions of local fans would enjoy the Games.

"Whatever poll is used, we are talking about more than 20 million supporters from Tokyo alone who will fill every venue, ensure a massive core of volunteers and create an incredible atmosphere to host the world's greatest sports event," he said in an email sent to Reuters.

Bookmakers' favourite Chicago comes second with 92 percent of public backing in the United States.

Rio, promoting the city's friendly atmosphere and the hosting of the 2007 Pan American Games as key reasons for holding a successful Games, has 89 percent of nationwide support, the report added. (Editing by John Mehaffey and Sonia Oxley)