A Navy veteran has been charged in connection with sending letters filled with ground castor beans to Donald Trump and other leaders.

William Clyde Allen, 39, marked the envelopes with "Jack and the Missile Bean Stock Powder" and packed them with the ground bean, from which the poison ricin is derived, before posting them to the president.

Letters were also sent to FBI director Christopher Wray, defence secretary Jim Mattis and the navy's top officer, Admiral John Richardson.

The FBI said all the letters tested positive for ricin, but all were intercepted and no one was hurt.

Authorities traced one of the letters back to Allen after he added his return address, investigators said.


Image: The Navy vet was charged with threatening to use a toxin as a weapon

Allen claimed he had also sent letters to Queen Elizabeth II, Vladimir Putin and the secretary of the US Air Force, but it is not clear if those letters have been found.

He told investigators he wanted to "send a message" and had purchased the beans to protect the US in case World War III broke out.

Allen has now been charged with threatening to use a biological toxin as a weapon.

Image: FBI investigators wear hazmat suits to enter the house in Utah

US attorney for Utah John Huber did not comment on Allen's mental state, but said: "When you're dealing with suspected ricin, this is nothing to trifle with."

Allen broke down during a hearing on Friday, as he told the judge his wife suffers with a spinal condition and described how he helps her put her shoes on every morning.

Image: His home was searched after the letters were traced back to him

Allen did not enter a plea. He faces life in prison if he is convicted on the biological toxin charge, one of five counts brought against him.

He is also charged with four counts of making threats through the mail, which carry 10-year sentences.

Image: The letters were filled with ricin, which comes from ground castor beans

Allen was arrested at his home in Salt Lake City, Utah on Wednesday. His case is expected to go before the grand jury.

He served in the navy from 1998 to 2002, and has a criminal record in Utah, including child abuse and attempted aggravated assault.