Parts of the Palace of Westminster were closed off this morning after smoke detectors in the basement of the historic building were activated.
Although the detectors were activated there was no fire and it is believed that the sensors were triggered by work being carried out overnight.
Security staff cordoned off parts of the building as a precautionary measure, amid fears that toxic substances such as asbestos could have been released, but the all clear was given shortly after 8am.
A Commons spokesman said: "Smoke detectors in the Palace activated in the early hours of Friday morning linked to overnight works in the basement area.
"While the alarms were being investigated, and as a precautionary measure, certain areas of the Palace were closed.
"Experts ran tests and at around 8am reassurance was provided so that the Palace could be accessed safely as usual."