SAN FRANCISCO » San Francisco’s mayor was accused by the FBI of taking bribes in exchange for favors, attorneys for a defendant in an organized crime case centered on San Francisco’s Chinatown said Tuesday.

In a court filing, Curtis Briggs, an attorney for Raymond "Shrimp Boy" Chow, cites as the source of the FBI’s allegation documents turned over to him by the government as part of the process of mounting a defense for his client.

Briggs is seeking to dismiss the indictment against Chow on the grounds that the government is selectively prosecuting him while letting other people caught in its probe go.

Mayor Ed Lee has not been charged with a crime. P.J. Johnston, a spokesman for the mayor’s 2015 campaign, said nothing in the filing suggests Lee did anything wrong.

"While it appears others may have tried to engage or ensnare Mayor Lee and any number of other people in their own wrongdoing, there’s absolutely nothing in today’s filing by Raymond Chow’s attorneys that suggests that Mayor Lee himself or his 2011 campaign did anything wrong or inappropriate," he said.

The campaign had done a complete audit and found no evidence to substantiate any allegations against the mayor or his campaign, Johnston said.

The documents accompanying Briggs’ filing do not appear to show the mayor directly soliciting or receiving a bribe.

Chow, the elected "dragonhead" of the Chinese fraternal group known as the Ghee Kung Tong, was arrested after a multiyear investigation by the FBI that also ensnared former state Sen. Leland Yee.

The FBI alleges the association was a racketeering enterprise and that undercover agents laundered $2.6 million in cash from illegal bookmaking through the organization.

Chow has pleaded not guilty to money laundering and other charges.

Yee pleaded guilty to racketeering last month.