Batista, the head of the EBX Group, had already donated R$10 million (£3.2 million) earlier in the campaign.

The 51-year-old Batista is Brazil's wealthiest man with an estimated fortune of US$16.6 billion (£10 billion) having built and lost a gold mining fortune before turning to iron-ore mining.

Forbes ranks Batista, who is half-German and who was formerly married to Luma de Oliveira, a model and former Playboy covergirl, as the 142nd richest man in the world.

Carlos Arthur Nuzman, the President of Rio's bid, said the new investment illustrates the confidence Brazilian entrepreneurs have in the project and their recognition of the significant commercial and broadcast opportunities that will be created if Rio hosts the Games.

He said: "We are in the final stages of the campaign and there’s a great sense of unity.

"We are honoured by the confidence shown by EBX and the other sponsors; it underpins the certainty of our bid and the widespread support in the business community.

"Since he first encountered Rio 2016, Eike Batista has become a very enthusiastic supporter."

With headquarters in Rio de Janeiro, the EBX Group is a holding company that develops and manages businesses in mining, energy, logistics, oil and gas, renewables and entertainment.

Batista said: "We believe that Rio is ready and will win the right to host the Games.

"The project is of critical importance for the city and country and we will remain committed, supporting the candidature, until the vote.

"My confidence in victory is even greater because of the dedication of President Lula, the Governor, the Mayor and the extraordinary team of the Rio 2016 Bid Committee."

As well as EBX, the Rio 2016 Committee is sponsored by Embratel, TAM and Odebrecht.

Rio is bidding against Chicago, Madrid and Tokyo.

The International Olympic Committee (IOC) is due to announce its decision at its Session in Copenhagen on October 2.