An envelope containing ricin, a very powerful poison, was addressed to the White House this week and intercepted before reaching President Donald Trump, US media reported on Saturday.
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"
FBI, US Secret Service and Postal Inspection Service are investigating suspicious letter received at government mail center
," federal police said.
"
At present, there is no security threat
," the FBI added in an exchange with AFP.
According to anonymous sources, cited by the
New York Times
and CNN, two tests carried out on the product found in this suspicious mail established that it was ricin.
Ricin is the most violent poison in the plant kingdom, 6,000 times more powerful than cyanide.
It is a deadly substance if swallowed, inhaled or injected, and for which there is no antidote.
According to the New York daily, investigators believe the mail came from Canada and they have identified a woman as a suspect.
Other federal agencies, located in Texas, have also received mailings containing this poison, according to the newspaper.