Two people were taken to hospital as a precaution, as detectives investigated a suspect package at Britain's parliament, police said in a statement on Monday.
"Specialist officers are in attendance and the package is being assessed," the statement said.
"London Ambulance Service attended and two people, a man and a woman, have been taken to hospital as a precaution."
A statement from the House of Commons said: "Today, a suspicious substance was investigated by the Met Police and was found not to be hazardous. The affected area was temporarily cordoned off but no evacuation was necessary. Two people attended hospital as a precaution."