WASHINGTON — The Internal Revenue Service has awarded an ex-banker $104 million for providing information about overseas tax cheats — the largest amount ever awarded by the agency, lawyers for the whistleblower announced today.

Former Swiss banker Bradley Birkenfeld is credited with exposing widespread tax evasion at Swiss bank UBS AG. Birkenfeld served roughly two and-a-half years in prison for a fraud conspiracy conviction related to the case, which resulted in a $780 million fine against the bank and an unprecedented agreement requiring UBS to turn over thousands of names of suspected American tax dodgers to the IRS.

“The IRS today sent 104 million messages to whistleblowers around the world — that there is now a safe and secure way to report tax fraud and that the IRS is now paying awards,” Birkenfeld’s lawyers, Stephen M. Kohn and Dean A. Zerbe, said in a statement.

“The IRS also sent 104 million messages to banks around the world — stop enabling tax cheats or you will get caught.”

Birkenfeld has become something of a cause celebre among whistleblowers because of the magnitude of his case and the fact that he was jailed after cooperating with authorities.