Federal prosecutors mocked ex-state Assembly Speaker Sheldon Silver’s attempt to get his corruption charges dismissed, writing in court papers filed Friday that the payments he received were kickbacks whether they were handed over as “cash in a suitcase or disguised as referral fees.’’

Silver has tried unsuccessfully to get the charges tossed in the past by claiming he violated no federal law by receiving fees for referring cases to a law firm.

“As much as Silver may wish otherwise, bribes, kickbacks and extortion are just as illegal in New York as they are in every other state,” the prosecutors wrote.

Silver resigned as Assembly speaker after he was charged in January.