Two people are believed to have glued themselves to the gate of an immigration centre in an attempt to stop the departure of a charter flight deporting people from the UK.
Ten anti-deportation activists gathered to protest at Colnbrook immigration removal centre near Heathrow airport, the Unity centre said.
The protesters formed a blockade in a bid to stop a bus carrying deportees from the centre being taken to Stansted airport for a flight to Nigeria, Ghana and Sierra Leone, the group added.
Police attended the scene on Tuesday evening for around five-and-a-half hours but no arrests were made.
London Fire Brigade also sent a fire engine to the scene.
A Met police spokesman said: "There were a small number of demonstrators in attendance at the immigration centre who had been there since 5.30pm.
"We were on the scene with the fire brigade in a monitoring role and there have been no arrests."