A group spokesman said: “Britain is now a hostile environment for all companies involved in the brutalisation and murder of Palestinians.
“Elbit Systems is one such company, but Teledyne Technologies are another major player.
“They supply surveillance equipment for Israel’s apartheid wall, and targeting systems for their fleet of combat drones.
“Tackling the imperialist hydra means cutting off all its heads, so we will shut down each and every company complicit in the ongoing colonisation of Palestine.”
A Dyfed-Powys Police spokesman said: “A large number of police are currently at an industrial site in Presteigne where there is an ongoing protest.
Damage has been caused to a building, and there are people on the roof. Officers are working to bring them down safely.
“Two people have been arrested.”
The disruption comes after the group disrupted the techUK Defence Winter Dinner only last night.
Five activists entered London’s Landmark Hotel and seized the microphone to broadcast their group’s pro-Palestinian message.
Palestine Action described itself as “a network of groups and individuals established to take direct action against properties owned by Israel’s biggest arms firm Elbit Systems. The mission is to shut Elbit down and end all British complicity in the illegal colonisation of Palestine”.
Elbit Systems and Teledyne Technologies were contacted for comment.