Protesters erected scaffolding last year

Trident Ploughshares, organisers of the annual summer event, has asked members to pledge non-violent opposition to nuclear weapons.

The campaign group, formed in 1998, said it has had several victories in its short history.

At previous summer camps, it said activists have breached base security, swum close to the Trident submarines and have conducted effective blockades of the base entrances.

In its three years of action, the group said it has damaged testing equipment, sabotaged a research barge and disarmed a nuclear warhead convoy truck.

Appalling weapons

The group's actions have sparked 1,300 arrests and activists have spent about 1,250 days in prison.

Spokesman David Mackenzie said campaigners were arriving from all over the UK, the US, Belgium and Finland to set up camp at Peaton Glen Wood, Loch Long.

He said: "Every day we get another indication that those in power are critically complacent about the threats to our planet, including the threat from appalling weapons like Trident.

"In that setting, peaceful and non-violent intervention by ordinary, responsible people is not merely legitimate, it is vital.

"We are delighted that more and more people are acting on this conviction."