Parts of the Houses of Parliament have been shut down while police investigate a suspected “chemical incident”.
Doors and windows are reportedly being closed after police said a “suspicious package” had arrived at the Palace of Westminster.
Nobody is currently reported to have been injured or made unwell in the incident.
A number of House of Lords peers are reported to be stranded on the House of Lords terrace overlooking the Thames, unable to re-enter the building.
The Parliamentary estate as a whole is still open and not currently on lockdown.
As of 2pm a police officer in a hazardous material suit was seen exaimining the suspicious package.
Other officers were also spotted on the scene, with the investigation appearing to proceed calmly.
There are unconfirmed reports that an envelope containing "white powder" was sent to a House of Lords peer.
The alert comes on the anniversary of the 7/7 bombings in London.
A spokesperson for the Metropolitan Police said: “A suspicious package has been delivered to the Houses of Parliament.
“Officers are at the scene examining the contents of the package.
“There have been no reports of any related injuries or illnesses at this time."
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