A letter sent to the US senate office has tested positive for the poison ricin, reuters has reported.
US senator Durbin said he was briefed by the FBI on an envelope that test positive for ricin.
The senator said he believed the letter was just one of suspicious letters that have been found.
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"People must be aware at all times that there are wild animals around them and they must make sure that their tents are properly closed."
The UK has been stripped of its top credit grade rating by Standard & Poor in the wake of its vote to leave the European Union.
Tonight: Showers will become confined to northern and western Scotland overnight leaving much of the country dry with clear spells.