The 75-year-old was arrested last week for alleged involvement in a vote-buying scandal connected to Rio's successful bid for the 2016 Olympic and Paralympic Games eight years ago. 

He is also accused of "corruption, money laundering and criminal organisation" and has stood down as President of Rio 2016 and the Brazilian Olympic Committee (COB) as he concentrates on clearing his name.

In a new development, Nuzman is accused of unsuccessfully requesting the use of Rio 2016 Organising Committee money to pay his own legal fees since the investigation into him began last month.

Nuzman's right-hand man Leonardo Gryner, the Rio 2016 general director, has also been kept under preventative detention after being arrested and accused of the same charges.

This decision by Judge Marcelo Bretas followed a request by the Federal Prosecutor's Office, who recommended that both officials not be granted any sort of bail in order to "preserve the environment of free collection of his performance and interference, which would surely be impaired with the freedom of Carlos Nuzman".

Nuzman is suspected by Brazilian prosecutors of being the main link between Arthur Cesar de Menezes Soares Filho, a businessman nicknamed "King Arthur", and Senegal's former International Association of Athletics Federations President Lamine Diack. 

Diack was a voting member of the International Olympic Committee (IOC) at the time Rio was awarded the Olympic and Paralympic Games at the IOC Session in Copenhagen eight years ago. 

De Menezes allegedly provided at least $1.5 million (£1.2 million/€1.4 million) through a company set-up by Diack's son, Papa Massata, to help solicit the votes of African IOC members in return for supporting Rio 2016. 

Brazilian Federal investigators also believe that Nuzman - an IOC member until he passed the age limit in 2012 - filed income tax returns in the last month for items including BRL480,000 (£118,000/$155,000/€129,000) found at his residence in five different currencies and for 16 one-kilogram gold bars deposited in Switzerland.

This, they concluded, was done to "give the appearance of transparency and lawfulness to assets that were hidden".

Nuzman denies all wrongdoing and has vowed to "defend his honour" and prove his innocence to exercise a right to defence which, he claims, has so far been "violated".

O'Globo also quoted investigators claiming that the total value of Nuzman's estate increased by 457 per cent between 2006 and 2016, with the most significant rises recorded over the last three years.

An increase of R$4.3 million (£1 million/$1.4 million/€1.2 million) was reportedly recorded for this year alone, of which R$3.9 million (£900,000/$1.2 million/€1.1 million) allegedly originated from a company based in the British Virgin Islands.

It appears that this latter allegation is a major reason why the officials have not been granted bail, with Swiss authorities having promised to assist the Brazilian investigation.

According to O'Globo, Judge Bretas ruled that "in the current phase of the investigation, the MPF presents robust evidence against Carlos Nuzman, which goes beyond mere collaboration and already indicates the practice of the crime of belonging to the criminal organisation".

This "robust evidence" includes an allegation that Nuzman had been trying to keep hidden or legalise parts of his undeclared assets to the Receita Federal, or Internal Revenue Service.

He also allegedly attempted to make the Rio 2016 Organising Committee pay his lawyer Nélio Machado R$5.5 million (£1.31 million/$1.71 million/€1.46 million) in "legal services", although this payment was not ultimately made.

Prosecutors record that Nuzman requested the hiring of the lawyer late last month and after the investigation was opened and his house searched on September 5.

It comes as organisers are still thought to owe debts of around R$132 million (£31 million/$41 million/€35 million) to suppliers and other companies involved in the Games.

The request was approved by the Rio 2016 Compliance Sector and then by a two thirds majority vote by the Board of Directors on September 27.

However, they also ruled that it was necessary to commission an external legal opinion to endorse the hiring, and their opinion ultimately led to the decision being overturned.

Machado told O'Globo, though, that he decided not to take the payment after learning that two members of the Board of Directors had opposed it, and is now defending Nuzman out of "solidarity".

Nuzman has already been suspended as an International Olympic Committee (IOC) honorary member and "withdrawn" from the Tokyo 2020 Coordination Commission as the investigation continues.

The IOC have also provisionally suspended the COB as well as their relationship with Rio 2016.