A leading union today called for a busy Tube station to be closed after claiming it had possibly been contaminated with anthrax and asbestos.
The Rail Maritime and Transport (RMT) union said there was a "potentially extremely dangerous situation" at Hammersmith station in West London.
Transport for London (TfL) accused the union of scaremongering and insisted there was no risk to passengers or staff.
RMT general secretary Bob Crow said staff had been told that potential traces of anthrax and asbestos had been found during refurbishment of a bar at the station, which serves the District, Piccadilly and Hammersmith & City lines.
Samples were currently being tested, the area had been boarded up and secured and staff had been told not to enter, said Mr Crow.
The union leader said in an email to London Underground (LU): "I have seen the email regarding the possible anthrax and asbestos contamination at Hammersmith.
"RMT health and safety reps have raised with me the inadequacy of the response from LU to this potentially extremely dangerous situation.
"I am emailing to request that the station be closed to avoid any potential risk to passengers or staff until such time as your checks and tests have been concluded."
A Transport for London spokesman said: "Anthrax has not been found at Hammersmith station, we have simply sent some very old horse hair building materials off for testing.
"This is standard industry practice and is a requirement of building regulations. Nonetheless we are being very cautious and the premises have been sealed off to staff and the public.
"To suggest that this site represents a risk to customers or staff is simply scaremongering."