NEW YORK (Reuters) - Goldman Sachs Group Inc GS.N was sued on Thursday by a former managing director who said the Wall Street bank retaliated against him and fired him after he complained about its dealings with an unidentified, "notorious European businessman."

FILE PHOTO: A view of the Goldman Sachs stall on the floor of the New York Stock Exchange in New York, U.S. on July 16, 2013. REUTERS/Brendan McDermid/File Photo

Christopher Rollins, now chief executive of BTIG Ltd, a London-based unit of investment banking and trading firm BTIG LLC, is seeking at least $50 million plus punitive damages in his complaint filed with the U.S. District Court in Manhattan.

The 2000 Harvard University graduate accused Goldman and Jim Esposito, promoted this week to global co-head of its trading business, of violating his rights as a whistleblower under the federal Dodd-Frank law, and also accused Goldman of defamation.

“The suit is without merit and we intend to vigorously contest it,” Goldman spokesman Michael DuVally said in an email, responding to a request for comment on behalf of the defendants and several bankers named in the complaint.

DuVally referred to a filing with a U.S. brokerage regulator that said Goldman discharged Rollins after he allowed unauthorized trades by a counterparty that had been denied a trading account because of compliance concerns.

Lawyers for Rollins did not immediately respond to requests for comment. Rollins had been Goldman’s co-head of trading execution for Europe, the Middle East and Africa.

In his complaint, Rollins said the European businessman claimed to have more than $1 billion to invest, and became a Goldman client after two senior bankers met him on his 200-foot (61 m) “superyacht” in the Mediterranean Sea.

Rollins said the bankers and former vice chairman Michael Sherwood “used their influence” to steer nearly $2 billion of transactions linked to the businessman past the bank’s anti-money laundering controls from Sept. 2015 to Aug. 2016.

But Rollins said Goldman “scapegoated” and suspended him after uncovering suspect trades involving a European company and linked to the businessman, who he claimed to know only socially.

The complaint said Esposito “decided that Rollins’ 16-year career with the Firm would be terminated on February 5, 2017,” after Rollins had begun reporting questionable activity to Goldman’s lawyers, the U.S. Securities and Exchange Commission and the U.S. Commodity Futures Trading Commission.

Rollins’ defamation claim arose from Goldman’s having allegedly provided “false and damaging information about Rollins to regulators, defaming Rollins to prospective employers,” the complaint said.

The case is Rollins v Goldman Sachs & Co et al, U.S. District Court, Southern District of New York, No. 18-07162.