Six men and three women were detained when police were called to the Glover Webb factory at Hamble, near Southampton, in the early hours of the morning. Later another man and woman, found within the perimeter of the factory, were also arrested. A spokesman for the company, part of the GKN group, said: "They daubed some slogans, all of which have now been washed off."
The spokesman added that the company was not directly involved in the arms trade, but built light armoured vehicles, some of which had been supplied to Indonesia after a government export licence had been obtained.
Among the protesters detained was said to be Angie Zelter - one of four women acquitted at Liverpool Crown Court last year of causing millions of pounds worth of damage to a BAe Hawk jet. In an earlier statement, Ms Zelter claimed that the Indonesian police and army were likely to use the armoured vehicles for "gross human rights abuses".