The US embassy in Stockholm was evacuated on Wednesday over a possible security incident, a spokesman for the mission told AFP, while police said a suspect envelope had sparked the scare. "We've evacuated the embassy while we are investigating a possible security incident," embassy spokesman Jeff Anderson said. "We are working together with the Swedish authorities." Swedish police said on their website that a patrol had been dispatched to the embassy after "a letter with unidentified content had arrived at the embassy". News agency TT reported the letter contained an unidentified white powder.