In another letter, Devlin-Brown asks that the bank treat the funds "as legally seized" by the FBI, saying that the government has probable cause that the gambling payments of U.S. residents had been directed to offshore illegal Internet gambling businesses, the AP reported.
A source at Citgroup familiar with the government request, however, confirmed the "bank has been contacted and is cooperating" with the authorities.
According to the alliance, the laws cited by prosecutors "appear to allege violations of the Wire Act and the Illegal Gambling Business Act" and not to a more recent piece of legislation on online gaming called the Unlawful Internet Gambling Enforcement Act.
Another player, Sam Friedman, a 24-year-old accountant in New York City who plays every night in tournaments on FullTiltPoker.com, said he realized the company had last week removed an option to deposit winnings directly into his Citibank account.
"There are lots of ways to deposit and withdraw money and payment options are always disappearing, but something didn't seem right," Friedman said.
"I can't believe the government is reaching into people's bank accounts like this," he said. "For a lot of serious players this is their lifeblood. This is how they make ends meet."
Both FullTiltPoker.com and PokerStars.com have reimbursed players who tried to cash out and were unable to.
"In light of recent events involving the freezing of certain accounts, Full Tilt Poker would like to assure all players that their funds remain safe and secure," spokeswoman Michelle Clayborn said in a statement.
"All players who were affected by the current situation have had their funds returned to their accounts," the statement said.
David, the World Series hopeful, said he had been reimbursed by PokerStars and given an additional 10 percent credit.
He used his own savings to buy into the World Series and will use the winnings from his championship game online to pay himself back as soon as he gets them, he said.