Ten Palestine Action activists have been arrested on suspicion of terror offences, police have said.
The arrests relate to the attack on Israeli defence firm Elbit Systems in south Gloucestershire in August.
Shortly after the incident on August 6, ten people were arrested and charged that same month. All ten were charged with criminal damage, aggravated burglary, and some were charged also with violent disorder and assault offences. They remain in custody awaiting trial.
On Tuesday, ten further people were arrested in connection with the attack; nine on suspicion of the commission, preparation and instigation of acts of terrorism, while a 72-year-old man from Hull was arrested on suspicion of preparation of terrorist acts, Counter Terrorism Policing South East said.