• Swiss attorney general says ‘53 suspicious banking relations’ uncovered • Investigation into 2018 and 2022 World Cup bids could take years • Fifa’s Sepp Blatter and Jérôme Valcke not being ruled out of investigation

Swiss investigators are looking into 53 possible cases of money laundering and 104 incidents of suspicious activity in Swiss bank accounts as part of their investigation into the awarding of the 2018 and 2022 World Cups.

The head of Fifa’s audit and compliance committee, Domenico Scala, has already reiterated that there could be a revote for 2018 World Cup in Russia and the 2022 tournament in Qatar if clear evidence of bribery emerged.

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The Swiss attorney general Michael Lauber, giving an update into the Swiss investigation that is running in parallel to an FBI inquiry that has already resulted in 14 executives being charged and plunged Fifa into crisis, said investigators were examining “nine terabytes” of data from Fifa’s Zurich headquarters and Swiss banks.

“I am well aware of the enormous public interest in our investigation. Equally enormous is the public interest in an independent criminal procedure,” Lauber said. “Our investigation is of great complexity and quite substantial. To give you an example: The SAG [Swiss attorney general’s office] has seized around nine terabytes of data. So far, our investigative team has obtained evidence concerning 104 banking relations; be aware that every banking relation represents several bank accounts.”

He warned there would be interviews of “all relevant people” and specifically did not rule out interviewing the Fifa president Sepp Blatter, who promised to step down in the wake of the US indictment, and the general secretary, Jérôme Valcke, who is under pressure over what he knew about a $10m payment from South Africa to the Caribbean that US prosecutors claimed was a bribe.

At a press conference in Bern, Lauber said that Swiss banks had fulfilled their obligations to report suspicious banking activity and that the Swiss investigation had not been instigated as a result of the FBI investigation.

The Swiss investigation into the controversial and chaotic World Cup bidding process – in which England lost out for the 2018 tournament and the US among the bidders for 2022 – was made public on the same day that US prosecutors alleged a “World Cup of fraud” stretching back two generations and dramatically arrested seven executives in Zurich.

It has seized data and documents during two visits to Fifa’s headquarters and collected documents from Swiss marketing agency Kentaro relating to a friendly between Brazil and Argentina in Doha in 2010.

Fifa argued that the Swiss investigation was as a result of it handing over documents relating to an investigation by its ethics committee chief, Michael Garcia, and that as such it was in fact the “injured party”.

“For the time being Fifa is the injured party, that is true. They filed the report and this is the actual status as we conduct investigations against unknown persons,” said Lauber, but he warned that could change.

“We didn’t start the investigation against Fifa. We started the investigations based on that [report] and based on a mutual legal assistance request from the US.”

Asked whether the Swiss investigation, which is clearly already broader in scope than Garcia’s given the Swiss prosecutors’ ability to examine bank accounts, would tally with Fifa’s release of the full Garcia report Lauber said he was working to his own timetable and was not concerned about “collateral damage” elsewhere.

“We are faced with a complex investigation with many international implications. The prosecution is ongoing and will take time,” he said. “It would not be professional to communicate at this moment a detailed timetable. The world of football needs to be patient. By its nature, this investigation will take more than the legendary 90 minutes.”

Lauber, who said the “huge and complex” investigation could take months if not years in places, also emphasised that the Swiss process was independent from the US procedure and that they would not automatically share documents and information.

A disputed summary version of Garcia’s investigation, which caused the US attorney to quit his post in frustration, raised question marks over Qatar’s bid but said that there was not sufficient evidence to strip it of the tournament.

The summary, written by the German judge Hans-Joachim Eckert, said that the Russian bid was unable to cooperate because it had returned its rented computers and lost all its emails.

Under intense pressure, Fifa agreed to publish the Garcia report in full with redactions but has yet to do so while ethics cases against individuals are ongoing.

Scala said last week in the wake of Blatter’s promise to step down as Fifa president that a revote on the 2018 and 2022 tournaments remained a possibility.

“If evidence should emerge that the awards to Qatar and Russia only came about thanks to bought votes then the awards could be invalidated,” said Scala, the independent chairman of Fifa’s audit and compliance committee, in an interview with the Swiss newspaper SonntagsZeitung. “This evidence has not yet been brought forth.”

Fifa’s chief ethics investigator Cornel Borbely, who took over after Garcia resigned in December, said he was prepared to widen the net if new evidence came to light.

He said in a statement: “The independent investigatory chamber of the Fifa Ethics Committee is carrying out several proceedings into football officials on suspicion of breach of the Fifa code of ethics based on the findings of the investigation into the decision for the 2018 and 2022 World Cups.

“Should new evidence come to light, the investigatory chamber will widen the group of suspects. The Investigatory Chamber has taken the necessary preparatory measures for this and is prepared to increase its staff numbers at any time if needed.”

Elsewhere, the Asian Football Confederation’s general secretary, Alex Soosay, has tendered his resignation with immediate effect. Soosay was suspended last month amid allegations that he ordered a cover-up during an investigation into the organization in 2012.