Frankfurt prosecutors are looking into German financial regulator BaFin's handling of collapsed payments company Wirecard, a spokesman for the prosecutor's office said on Wednesday.
Prosecutors and federal police made an unannounced visit to BaFin's headquarters on Wednesday to hand over a letter requesting information, the spokesman said.
BaFin has faced widespread criticism for failing to spot wrongdoing ahead of the collapse of the payments company, and its chief is stepping down.
BaFin declined to comment.
"We have received several letters from concerned citizens asking for charges against unnamed people from the BaFin," the spokesman for the prosecutor's office said.
The complaints revolve around an alleged lack of oversight of Wirecard AG and Wirecard Bank, he said, adding there had also been complaints about the alleged use of insider information in the trading of Wirecard securities.
"We are looking into these charges," he said. "We haven't opened a formal criminal investigation."
The involvement of Frankfurt prosecutors raises further questions about Germany's supervision of a company that began by processing payments for gambling and pornography before becoming a star of "fintech" - financial technology - and finally Germany's biggest fraud case.
Prosecutors also visited another unidentified German federal authority and an unidentified bank with requests for information, the spokesman said.
(Reporting by Tom Sims and Patricia Uhlig. Editing by Maria Sheahan and Mark Potter)
