A poisoned envelope containing the ricin was sent to the White House and was believed to have come from Canada, the New York Times reported on Sunday.
The incident happened weeks before the US election and was stopped before it reached the heavily guarded area.
Several local media reports claimed that the security services found ricin, a deadly poison, on the envelope on Saturday. The local media is sourcing a federal official on the matter.
"U.S. Secret Service and U.S. Postal Inspection Service partners are investigating a suspicious letter received at a U.S. government mail facility. At this time, there is no known threat to public safety," FBI source has been quoted in some media.
The Trump administration is yet to comment on the reports.