Update: South Kensington Tube station has reopened following a security alert that had brought the entire Circle Line and parts of the District Line to a halt.
An alert was posted just before 1:30 this afternoon, with TfL saying there would be no service while they responded to the incident.
Police were quickly on the scene and the west London station had been evacuated, with the area around the station had been cordoned off.
But it appears to have been a false alarm: a suspect package had been reported by a member of staff. All three lines have now reopened, although TfL is reporting severe delays as a result of the disruption to service.
Earlier in the day, Russell Square station was closed because of a security alert.
Emergency services are on high alert following the attacks in Tunisia, France and Kuwait last week.
The assistant commissioner Mark Rowley, National Police Chiefs' Council lead for counter terrorism, said at the weekend: "In the UK, the threat from international terrorism remains severe, meaning an attack is highly likely. Due to this level of threat the police service is already operating at a heightened state of alert and our security plans for public events reflect this readiness."