"The strength of the evidence against him is overwhelming ... To be clear, investigators literally found drugs on the pouch where the defendant had kept his gun," the prosecutors were quoted as saying by the broadcaster.
An FBI lab has identified the substance removed from a brown leather case as cocaine and the incriminating discovery was made last year, the broadcaster wrote.
The prosecutors asked a judge on Tuesday to turn down Hunter Biden's efforts to dismiss gun charges, the broadcaster added.
US President Joe Biden's son is refusing to plead guilty to allegedly lying about his drug use while filling out a form when purchasing a gun in October 2018. In doing so, Hunter Biden revealed in his memoirs that he was addicted to drugs at the time.