French prosecutors investigating corruption in world athletics have expanded their remit to include the bidding and voting processes for the Rio 2016 and Tokyo 2020 Olympic Games, the Guardian can reveal.

Up to now the investigation into wrongdoing at the International Association of Athletics Federations has led to multiple arrests including that of the former president Lamine Diack and an international warrant being issued for his son, the organisation’s former marketing consultant Papa Massata Diack. However, it is now understood that French financial prosecutors are also looking into the bidding processes that concluded in 2009 with the 2016 Olympics being awarded to Rio de Janeiro and in 2013 with the 2020 Games being awarded to Tokyo.

It is the first sign that the crisis may spread beyond the IAAF and create serious issues for the International Olympic Committee, which has regularly insisted it is fully reformed following measures taken in the wake of the Salt Lake City bribery scandal in 1999.

The Guardian revealed in January that Papa Massata Diack had appeared to arrange for “parcels” to be delivered to six IOC members in 2008 at a time when Qatar was bidding for the 2016 Olympic Games, though it failed to make it beyond the shortlisting stage. Qatar has denied any wrongdoing.

The email went on to appear to suggest that six individuals, referred to only by initials but these correspond with those of six members of the IOC at the time, had requested “to have their parcels delivered through Special Adviser in Monaco”.

Sources said the “special adviser” in question was likely to be Lamine Diack.

The French investigation is understood to be at an early stage but is likely to examine the role of Diack Sr, an IOC member from 1999 to 2013, in the bidding races.

Obvious areas of interest, based on the email from Diack Jr to a Qatari official seen by the Guardian, could include whether Lamine Diack and his son were able to act as intermediaries between bidding cities and a group of IOC members.

Diack Sr, arrested in December, was accused of accepting more than €1m in bribes to suppress positive drug tests as part of a conspiracy aimed at delaying the sanctioning of Russian athletes.

Papa Massata Diack was accused of facilitating the payment of bribes and Gabriel Dollé, the former head of the IAAF’s anti-doping unit, was also arrested.

A spokesman for the IOC said: “The IOC has been in close contact with the French prosecutors since the beginning of this investigation last year. The IOC’s chief ethics and compliance officer had already asked for the IOC to be fully informed in a timely manner of all issues that may refer to Olympic matters and has already applied to become a party to the investigations led by the French judicial authorities.”

Rio 2016 organisers said there were no direct allegations against its bid. “Rio won the Games because it had the best project, both from the point of view of the organisation of Games and the legacy,” said a spokesperson. “Rio beat Madrid by a clear margin of 66-32 [votes], which excludes any possibility of a manipulated election.”

The second part of an independent review by the former World Anti-Doping Agency president Dick Pound found that the 82-year-old Lamine Diack oversaw a parallel system of governance within athletics’ governing body, saying: “Lamine Diack was responsible for organising and enabling the conspiracy and corruption that took place in the IAAF. He sanctioned and appears to have had personal knowledge of the fraud and the extortion of athletes carried out by the actions of the informal illegitimate governance structure he put in place.”

Diack Jr had previously responded to the allegations, protesting both his own and his father’s innocence. “He [Lamine] has never been involved in any corrupt system to extort money from athletes, I totally reject that,” he told the BBC in December. He also dismissed any suggestion that he had asked for money from Qatar in 2011. “I have a very longstanding relationship with Qatar that dates to 1995, so I don’t need to send an email when I need something from Qatar,” he told the BBC. “I have all the right people’s contacts and I can go straight to them. So I reject it totally.”

Possible wrongdoing in the 2020 race was referred to in a footnote to Pound’s report that suggested Diack dropped his support for Istanbul and switched to Tokyo because a Japanese sponsor signed a deal with the IAAF.

At the time, Tokyo 2020 said the claims were “beyond our understanding” and Istanbul’s bid said it did not believe it was a factor in their defeat. The IOC said it would examine a transcript of the conversation on which the claims were based.

French prosecutors are believed to be pursuing a twin-track approach: pursuing those they believe to have been involved specifically in the IAAF corruption while also considering a host of wider, related issues as part of a second strand of inquiry.

As part of their investigation, the team of financial prosecutors are also believed to be examining the bidding races for the 2017 World Athletics Championships, to be staged in London, the 2019 edition, to take place in Doha, and the 2021 event scheduled for Eugene, Oregon. All have proved controversial in their own ways.

The Guardian revealed in December 2014 that Papa Massata Diack appeared to ask for $5m from Doha at a time when it was bidding against London. He denied ever making any such request.

To secure the 2019 world championships, Doha offered a last-minute legal inducement in the form of £23.5m in sponsorship cash from an unnamed bank – prompting criticism from rival bidders.

The 2021 world championships were awarded without a tender process after Lamine Diack decided to accelerate the award of the event so that it could be taken to the US. The decision was unpopular with prospective rival bidders from Gothenburg, who accused the IAAF of a “complete lack of process”.

The role of Sebastian Coe, Diack’s successor and the current IAAF president, also came under scrutiny because of his close links to Nike, which has its headquarters near Eugene. In November, Lord Coe told the BBC that he “did not lobby anyone” over Eugene’s bid, but “encouraged them to re-enter another bidding cycle as they had a strong bid”. The US city had lost out to Doha in the 2019 process.

The news comes as the IOC gathers for a series of important executive board meetings five months before the Rio Olympics. Preparations have been hit by a downturn in Brazil’s economy, fears that a crucial metro link will not be finished in time, water pollution concerns, sluggish ticket sales and the impact of the Zika virus.

The IOC president, Thomas Bach, has made his Agenda 2020 reforms a priority since he was elected in 2013, as part of an attempt to make bidding for the Olympics more transparent and less expensive amid growing public scepticism about the benefits of hosting the Games.