Swiss police have raided Uefa’s headquarters in Nyon to seize details of a TV rights contract signed by the Fifa president, Gianni Infantino, following the Panama Papers leak.

The files, seen by the Guardian, show that Infantino – formerly director of legal services at Uefa, European football’s governing body – co-signed a TV contract in 2006 with two businessmen who have since been caught up in football’s global corruption scandal. Uefa, which has denied any wrongdoing, said it is cooperating fully with the Swiss police.

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The office of the attorney general of Switzerland (OAG) said the search on Wednesday was “motivated by the suspicion of criminal mismanagement” relating to the sale of TV rights but that “no specific individual is being targeted by these proceedings”. The OAG also revealed a separate location was searched and that authorities had already been investigating the rights acquisition before further details from the Panama Papers were published.

A statement read: “The suspicion is based on the result of findings that have emerged from other proceedings, as well as the corresponding financial analyses carried out by the OAG. Current publications in the media subsequently revealed still other elements that made it possible to complement the existing findings in a decisive manner.”

According to records, in 2006 Uefa concluded offshore deals through its marketing partner Team with one of the indicted figures at the heart of an alleged “World Cup of fraud”, despite previously insisting it had no dealings with any of them.

The Ecuadorian rights to the Champions League, the Uefa Cup and the Super Cup were acquired by an Argentinian company called Cross Trading. It immediately sold on to broadcaster Teleamazonas for about three or four times the amount paid for them. The contracts covered the period from 2003 to 2006 and from 2006 to 2009.

Uefa said on Tuesday night that Infantino, elected Fifa president in February as successor to Sepp Blatter, was “dismayed that his integrity was being doubted” in media coverage of the case. The Football Association, who backed Infantino as president earlier this year, did not comment when contacted on Wednesday.

Infantino later put out a statement which said that: “If my determination to restore football’s reputation was already very strong, it is now even stronger.

“I welcome any investigation conducted into this matter.” He added: “For the sake of transparency and clarity, it is essential that all elements of this dossier are disclosed, as Uefa has done.

“Based on these documents, it is clear that all contractual matters were conducted properly by Uefa.

“Should I be required to contribute to bringing further clarification on the matter, I will of course gladly do so.

“It is in my interest and in the interest of football that everything should come to light.”

The Mossack Fonseca documents detailed a 2006 contract to sell the rights for Ecuador. The deal was with two figures who have since been accused of bribery as part of the US investigation into corruption at Fifa. Hugo Jinkis and Mariano Jinkis, his son, are currently under house arrest in Argentina.

Cross Trading, the Jinkis’s Argentinian company, which was registered in the South Pacific tax haven of Niue, bought the rights for 111,000 US dollars, then immediately sold them to the Ecuadorian broadcaster Teleamazonas for $311,170.

Uefa had initially denied doing business with any of the 14 individuals indicted by the FBI, but admits now its response was incomplete. After a full review of thousands of commercial contracts, it accepts the deal was done as part of an “open tender” – a process conducted by Team Marketing on behalf of Uefa – and the rights were sold to the highest bidder.

Uefa, which released internal documents to back up their claims that the auction was open and transparent, said: “Neither Team nor Uefa had any reason to believe that there was anything suspicious or untoward about an agency relationship between Cross Trading and Teleamazonas.

“At the time when Uefa initially responded to these requests from the media it had not had the opportunity to review the (thousands) of commercial agreements it has concluded over the years, and so the initial information given was inaccurate and incomplete. Uefa apologizes for this oversight. There is, we repeat, absolutely NOTHING in this story which could in any possible way serve to undermine the integrity of either Uefa or Gianni Infantino.”

It said any bilateral deals between Teleamazonas and Cross Trading were “their business, not ours”. “We do know that [it was the] best offer for these FTA [free-to-air] rights in Ecuador. And that’s why we took it.”