Television channels including Channel 4 and Channel 5 were been disrupted in the middle of Saturday evening shcedules after the evacuation of a technical facility that plays out programmes and adverts.
On-demand services such as More4 have also been affected, with many viewers unable to watch programmes and others reporting flashing or frozen images.
The problem was caused by a fire alert at a transmission facility in White City, the former BBC headquarters now used by independent studios and production companies.
“Channel 4 and More 4 are currently off air due to a technical problem,” the channel tweeted as viewers complained of blank screens. “We are working to restore them as quickly as possible.”
S4C, the Welsh language public service TV broadcaster, also tweeted it was facing issues due to a fire at a distribution centre in London.
It said: “Unfortunately following a fire at a London distribution centre we are experiencing technical problems. Apologies.”
Red Bee Media, which handles transmission services for Channel 4 and Channel 5, said disruption was due to an “activation of the fire suppression systems” on Saturday evening.
A spokesperson said: “We confirm that all staff at our broadcast centre in West London were safely evacuated following activation of the fire suppression systems.
“As a result of this incident and the automatic safety measures set in motion at the time, several services originating from the broadcast centre have been disrupted.
“London Fire Brigade attended the scene, and once they had determined that the building is safe, people were allowed to return to the building.
“We are continuing to work to restore all services and remedy any issues caused by this incident.”