The former FIFA President and the longest serving member of the IOC, claimed that among those who have promised to back Rio when the election is held in Copenhagen on October 2 are China’s Zhenliang He, Timothy Fok from Hong Kong, Mohammed Mzali from Tunisia and Mexico’s Mario Vazquez Rana.

The 93-year-old Havelange, who has been an IOC member since 1963, has been busily contacting members to help drum up support for Rio, who are now considered the favourites to follow London 2012 and host the 2016 Olympics.

They have moved ahead of Chicago, the long-time front-runners, and the two other bidders, Madrid and Tokyo, and there is widespread enthusiasm for Rio staging the Games, Havelange claimed during an interview broadcast on TV Bandeirantes, a television station based in São Paulo.

He said: “I have received 20 replies and they all say they plan to vote for our bid.

"A letter from Zhenliang, from China, mentions, ‘I will never let you down’.

"The same from Fok.

"I had a gorgeous reply from Mzalii.

"Another one from Olegario [Vazquez Rana].

"This letter made me burst into tears."

There are 106 IOC members eligible to vote in the Danish capital but those from countries with bidding cities, such as Havelange, are not allowed to enter until their candidate has been eliminated.

It is estimated that the winning city will need around 50 votes.

Havelange, who competed as a swimmer for Brazil in the 1936 Olympics in Berlin and played in their water polo team at Helsinki in 1952, was President of FIFA between 1974 and 1998 and oversaw a number of major innovations in the sport, including taking the World Cup to previously uncharted countries, such as the United States.

He was also instrumental in persuading FIFA to award the 2014 World Cup to Brazil.

Havelange's comments, though, have raised eyebrows among Rio's rivals.

It is unusual for any bid city to reveal so publicly which members they expect to vote for it.

Doug Arnot, a senior vice-president of Chicago 2016 who is currently travelling round the world lobbying before next week's vote, said: "If I were to say that, I would be sent home from wherever I was probably and chastised severely."

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