An anti-Muslim letter has been linked with the suspicious package sent to an MP's office this afternoon, which resulted in two people being hospitalised.
The Metropolitan Police were called shortly before 1pm to reports of a suspicious package at Norman Shaw Buildings, which are part of the Palace of Westminster complex. It has since transpired the package was discovered in was discovered in Labour MP Mohammad Yasin’s office.
"Specialist officers attended and the package was assessed. The substance was deemed not to be hazardous to health," the Met Police said.
"The London Ambulance Service attended and a man and a woman were taken to a central London hospital as a precaution.
"The incident, which was contained to one room, is in the process of being stood down."
During a hate crime debate in the House of Commons about letters encouraging recipients to take part in "Punish a Muslim Day", MPs suggested the attack was related.
Conservative backbencher Michael Fabricant said: "Can I ask the house to think of the office of MP for Bedford. There was an incident in this place earlier today, Norman Shaw North, which involved him and his staff. It may or may not be connected - but we think it might be - to this letter, we think it may be.
"We must pull together and ensure it does not happen, not only here but also throughout the country," he added.
Answering on behalf of the government, home office minister Victoria Atkins added her best wishes to those affected, adding that she had received a note saying the package was not hazardous "which must be a significant relief to those involved".
According to Tell Mama UK, which monitors anti-Muslim activity, people in Bradford, Leicester, London, Cardiff and Sheffield have reported being sent the letters. The act is now being investigated by police as a hate crime.
Atkins said the letters were being investigated "very, very carefully", adding "the full force of the law is being applied".