Swiss authorities are reviewing 133 reports of suspicious financial activity linked to the decisions by soccer's ruling body to let Russia and Qatar host the 2018 and 2022 World Cup finals, said the Swiss Office of the Attorney General (OAG).

That was up from the 103 cases the OAG had reported in August in its investigation of suspected corruption at Fifa, whose headquarters are in Zurich.

Russia and Qatar, a small desert country with no real soccer tradition and where daytime temperatures can top 40 degrees Celsius (104F), have denied wrongdoing.

An OAG spokeswoman said by email in response to a Reuters query that the suspicious activity reports came from a Swiss financial intelligence unit called the Money Laundering Reporting Office Switzerland (MROS).

"These reports are related to the ongoing criminal proceedings around the allocation of the Football World Cup 2018 and 2022," she added.

US federal prosecutors are conducting a parallel investigation into Fifa's financial conduct, and have indicted 27 soccer officials over multimillion-dollar bribery schemes for soccer marketing and broadcast rights. Twelve people and two sports marketing companies have been convicted.

That investigation is also looking into the flow of suspicious money through the banking system. The Financial Times reported that prosecutors were threatening to punish banks for failing to report suspicious activity in Fifa-related accounts.

Acting under US requests for legal assistance, Swiss justice officials have agreed to share bank information with US prosecutors in five cases, a spokesman for the Federal Office of Justice in Berne said. No information has changed hands yet, because account holders have appealed.

The names of the account holders, the banks involved and the amount of money frozen in the probe have not been released.

US Department of Justice indictments indicate that conspirators made transfers to accounts in at least two Zurich banks: Bank Julius Baer and the Swiss unit of Israel's Bank Hapoalim BM.

Big Swiss banks UBS and Credit Suisse say they have received inquiries from authorities concerning their banking relationships to certain people and entities linked to Fifa, and that they are cooperating.

Fifa President Sepp Blatter, his deputy Jerome Valcke and European soccer boss Michel Platini have all been suspended by Fifa's internal ethics watchdog. None of them has been charged with a crime, and all deny any wrongdoing. - Reuters