FIFA President Sepp Blatter arrives for a news conference aside of the so-called "Sepp Blatter tournament" in Blatter's home-town Ulrichen, Switzerland, August 22, 2015. REUTERS/Denis Balibouse

ZURICH (Reuters) - Swiss authorities have received more than 100 reports of suspicious financial activity linked to FIFA's decisions to let Russia and Qatar host the 2018 and 2022 World Cup tournaments, the Swiss attorney general's office said on Saturday.

Switzerland's Office of the Attorney General (OAG) is investigating corruption at Zurich-based FIFA and its decisions on who would stage the World Cup. Both Russia and Qatar have previously denied wrongdoing.

"I can confirm that the OAG received so far 103 suspicious financial activity reports regarding the allocation of the Football World Cup 2018 and 2022," an OAG spokesman said in an email.

In July, the OAG said it had received 81 reports of suspicious financial activity for its investigation.

News of the additional reports was first reported by Swiss newspaper Tages-Anzeiger.

On Friday, Reuters exclusively reported that the Swiss investigation had hit some roadblocks, according to U.S. and European sources familiar with the matter.

(Reporting by Joshua Franklin; Editing by Gareth Jones)