Sepp Blatter and Michel Platini, once the two most powerful men in football, are facing jail after being formally charged with fraud and other offences over the £1.3 million (NZ$2.5m) payment that ended their careers.

Following a six-year criminal investigation begun in the wake of the Fifa scandal, the Office of the Attorney General of Switzerland (OAG) announced on Wednesday it had filed an indictment against the world governing body's former president and his heir apparent.

Blatter, 85, and Platini, the 65-year-old France icon, were facing trial within months at a federal criminal court in Bellinzona.

The pair have always denied any wrongdoing over the 2 million Swiss Francs payment, made the same year as Blatter's 2011 re-election.

But the OAG said in a statement: "This payment damaged Fifa's assets and unlawfully enriched Platini."

If convicted, Blatter and former Uefa president Platini would join a rogue's gallery of senior football officials guilty of criminal offences since an FBI-led investigation resulted in dramatic dawn raids on Fifa's luxury Zurich hotel in 2015 and the extradition of many of them to the United States.

Wednesday's charges came days after a six-year ban from football imposed on Blatter over what was ruled a "disloyal payment" had expired – although he was handed a further six-year ban earlier this year for other offences.

Platini was also banned for receiving the money – his punishment expired two years ago – after both men were cleared by Fifa's ethics committee of more serious corruption charges.

But criminal proceedings initially opened into Blatter alone continued to escalate, with Platini joining him under formal investigation last year before fraud was added to the list of suspected offences.

Both men have repeatedly insisted the £1.3 million was back-pay for Platini's work as an adviser to Blatter during the latter's first term in office between 1998 and 2002.

The written contract for the work stated Platini was to be paid 300,000 Swiss Francs and made no mention of any back-pay, a deal he and Blatter say they struck "orally" because Fifa was struggling financially at the time.

Blatter said on Wednesday: "I look forward to the trial before the Federal Criminal Court with optimism – and hope that this story will come to an end and that all the facts will be properly dealt with."

Platini branded the charges against him "unfounded and unfair" and a culmination of "six years of judicial abuses unworthy of the rule of law", adding that he had "complete confidence" in the outcome of any trial.