The needle is believed to have been obtained secretly and is apparently being offered around Las Vegas auction houses.
Michael Jackson’s family are said to have been informed by lawyers representing the unnamed seller and are reportedly desperate to stop the sale.
The bizarre artifact could go under the hammer on June 25 – the first anniversary of the singer’s death in Los Angeles.
His personal doctor, Conrad Murray, 57, has been charged with involuntary manslaughter after allegedly administering drugs such as Valium, lorazepam and propofol to the troubled star.
An autopsy found that Jackson died from “lethal levels” of propofol, a powerful anaesthetic. The syringe set to go on sale is said to be the one used to administer the fatal dose.
A source told The Mirror: “This is one of the sickest lots ever put up. The syringe is no longer needed in the inquest or in Murray’s forthcoming trial but the moral implications don’t bear thinking about.