A judge threatened today to drain the prison account of a Sept. 11 scammer unless he coughs up about $400,000 stashed in a bank in India.

Natarajan Venkataram, a former top official in the city Medical Examiner’s Office, was ruled in contempt of court for failing to surrender all the cash he stole from a program to identify victims of the terror attack that felled the Twin Towers.

Manhattan federal Judge Naomi Reice Buchwald cited the “historical pattern of (Venkataram’s) efforts to thwart the city’s recovery of the embezzled funds through delay and even deception.”

She gave him 10 days to release the overseas funds or face a $50-a-day fine that “will be imposed as a lien on any prison account balance over $25.”

Venkataram is currently serving 15 years in the slammer for his ghoulish scheme.

bruce.golding@nypost.com