About 100 anti-nuclear protesters tried to block the main entrances to the Royal Navy base.

Among those arrested was William Wolfe, leader of the Scottish National Party from 1969 to 1979.

The demonstration was organised by Trident Ploughshares 2000 as part of their campaign to phase out Britain's nuclear weapons by next year.

'Business as usual'

The Ministry of Defence played down the incident.

"The protest didn't cause any major problems - it was very much business as usual. We haven't suffered any disruption at all," said a spokeswoman.

The protesters, who said they are committed to non-violent action, were joined by Labour MP Dennis Canavan and the Church of Scotland minister, the Reverend Norman Shanks, leader of the Iona Community.

The head of the Scottish Socialist Party, Tommy Sheridan, also attended.

Mr Canavan said: "I support the Ploughshares campaign because the Trident weapon system is a threat to world peace.

"Even its threatened use is a crime against humanity. The money would be better spent on essential services such as housing, health and education."