Three poison-tainted, hand-addressed letters postmarked on the same day in Spokane, Washington, were mailed to President Barack Obama, a federal judge in Spokane and a post office in that city, the FBI says.

A fourth letter sent to Fairchild Air Force Base near Spokane is being analysed for possible ricin contamination and the FBI is trying to locate a fifth letter it believes was mailed to a Central Intelligence Agency (CIA) location in McLean, Virginia.

Matthew Ryan Buquet (37), accused of sending one of the letters, containing both ricin and a death threat to U.S. District Judge Fred Van Sickle, was arrested May 22. Charged last week with one count of mailing a threatening communication, He pleaded not guilty and is held without bail in Spokane. The Obama letter was intercepted on May 22, along with a similar letter sent to the Air Force base, the Seattle FBI office said on Thursday in a written statement.

Officials said on Thursday that another suspicious letter mailed to the White House was similar to two threatening, poison-laced letters about the gun control debate sent to New York Mayor Michael Bloomberg.

The letter was addressed to Mr. Obama and was intercepted at a White House mail screening facility, the Secret Service said. Two similar letters sent to Mr. Bloomberg in New York and his gun control group in Washington contained traces of ricin.

It wasn’t immediately clear whether the Obama letter intercepted on Wednesday contained ricin. New York Police Commissioner Raymond Kelly said on Thursday that all three letters apparently came from the same machine or computer. — AP