Leonardo, an Italian company on Crewe Road, supplies military technology to Israel.
This incudes components for F-35 fighter jets, which have been used to bomb Gaza.
Shortly after 6am on Monday, campaigners from the Shut Down Leonardo Edinburgh group could be seen parking a van at the site.
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One activist appeared to be locked inside while another said they were “locked” to the top of the vehicle.
The factory was also targeted with glass jars which were filled with red and green paint, in an attempt to block access and halt production.
Police are currently in attendance at the scene and enquiries are ongoing.
In a video shared on social media, one of the activists taking part in the blockade said: “I’m taking direct action today at Leonardo’s weapons manufacturer in Edinburgh where we’re looking to halt the production of the F-35 component parts that are made here and used to indiscriminately massacre civilians in Gaza.”
They added: “I’m locked on to the top of the van. We’re looking to shut down the factory for as long as possible.”
The protest comes after the group took similar action on July 15, when protesters drove a van into the security fence of the same factory.
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Images showed the front of the vehicle sticking through the fence, with a Palestinian flag draped over the rear of the vehicle.
A Police Scotland spokesperson said: “Around 6.15am on Monday, August 18, we were called to a report of a protest outside a business premises in the Crewe Road North area of Edinburgh.
“Officers are in attendance and enquiries are ongoing.”
