Protesters breached the runway at London Stansted Airport to stage a pro-migrant demonstration.
A group of eight protesters blocked a flight chartered byt the government to deport a group of asylum seekers to Nigeria and Ghana.
A Facebook Live stream showed the protesters chained together in front of a passenger jet.
In a press release, the group said the activists were from three organisation; End Deportations, Lesbians and Gays Support the Migrants and Plane Stupid.
They said they blocked the non-commercial runway at Stansted "in an attempt to halt a mass deportation to Nigeria and Ghana".
The flight includes people who "fear for their lives and have claimed asylum".
According to FlightRadar24 which monitors flight data, all flights to Stansted are currently circling or being diverted to Luton Airport.
Police officers can be seen at the incident attempting to remove the protesters.
The group were heard chanting: "No borders, no nations, stop deportations"
Stansted Airport said police had contained the incident but flights were suspended while they carried out further inspections.
The protest was on a "remote part of the airfield" not by the main passenger terminal, a spokesman for the airport said.
He added: "Flights are currently suspended but there have not been any affected at the moment as it is a quiet period.
"The police have contained whatever the protest is and they are just carrying out further inspections.
"We hope to resume operations fairly shortly."
A Home Office spokesman added: "We respect everyone's right to peaceful protest but we are clear that removal is an essential element of an effective immigration system.
"We expect those with no legal basis to remain in the UK to leave voluntarily but if they do not, we will seek to enforce their departure."
According to the Migration Observatory, in 2015 there were 40,896 people who were removed from the UK or departed voluntarily after the initiation of removal.
The UK has been using charter flights to deport people since 2001.
The government does not publicly publish the number deported via charter flights, but a Freedom of Information request found 1,877 people were deported on charters in 2015.
Pakistan is the most common destination, but Kosovo, Albania and Jamaica have also been involved.