Five activists who caused £180,000 damage to an arms factory were acquitted after they argued they were seeking to prevent Israeli war crimes.

The five were jubilant after a jury found them not guilty of conspiring to cause criminal damage to the factory on the outskirts of Brighton.

The five admitted they had broken in and sabotaged the factory, but argued they were legally justified in doing so.

They believed that EDO MBM, the firm that owns the factory, was breaking export regulations by manufacturing and selling to the Israelis military equipment which would be used in the occupied territories. They wanted to slow down the manufacture of these components, and impede what they believed were war crimes being committed by Israel against the Palestinians.

After being acquitted, one of them, Robert Nicholls, told the Guardian: "I'm joyful really, at being a free man. The action was impulsive really, we just wanted to do something that would make a real difference to the people of Palestine."

Another, Ornella Saibene, said: "I've felt very peaceful all the way through the trial because I'm proud of what I've done. It was the right thing to do."

They are the latest group of peace and climate-change activists to successfully use the "lawful excuse" defence - committing an offence to prevent a more serious crime - as a tactic in their campaigns. The acquitted are Nicholls, 52, Tom Woodhead, 25, Harvey Tadman, 44, Ornella Saibene, 50, all from Bristol, and Simon Levin, 35, from Brighton. They had decided to act last January after three weeks of Israeli military manoeuvres against Gaza in which many Palestinians were killed. According to a UN investigation by former South African judge Richard Goldstone, Israel committed war crimes by deliberately attacking civilians during the offensive known as Operation Cast Lead.

In his summing up, Judge George Bathurst-Norman suggested to the jury that "you may well think that hell on earth would not be an understatement of what the Gazans suffered in that time".

The judge highlighted the testimony by Caroline Lucas, the Green MP for Brighton Pavilion, that "all democratic paths had been exhausted" before the activists embarked on their action...