Intruders gained access to a BBC studio during a live broadcast.
The corporation said that it was investigating after several people had gained unauthorised access to the studio at New Broadcasting House near London’s Oxford Circus.
A group of five people got into the studio at 7.30pm on Friday while the BBC News Channel was using it, but were not seen on air.
They apparently left of their own accord and no-one was hurt in the incident.
A BBC spokeswoman said: “We take security very seriously and are urgently investigating how several individuals were able to gain access to a studio.
“No-one was hurt and there was no interruption to broadcasts.
“We have already taken further security measures and will take any other necessary steps.”