THREE protesters were arrested today after an anti-nuclear banner was draped across the roof of the Scottish Parliament.

A lone activist remained chained to the roof this morning after the Faslane peace camp activists climbed up the Holyrood building and unfurled the No Trident' sign at 8.15am.

Parliament staff removed the banner around 15 minutes later and Lothian and Borders Police arrested three of the activists.

The protest in Edinburgh came hours before a vote on the future of Trident in the Commons tonight and as demonstrators also gathered at the Faslane submarine base on the Clyde.

Speaking from the Parliament roof above the main entrance, protester Seth Ebdon said: "We've been planning this over the past week or so. I don't know how long I'll be here - all day if necessary."

Fellow Faslane camp resident Stuart Kerr, 29, said: "We want to raise awareness so that as many people as possible know about the vote today about Trident."

The Scottish Parliament said parliamentary business was not considered to be at risk.

The incident came as dozens of demonstrators - mainly students - were gathered at the main gate of the Faslane submarine base.

Four protesters who ran towards the gate were stopped and then carried away by police.

Strathclyde Police said three women and one man had been arrested.

An Edinburgh University student named only as Jake, 21, said: "We're here today to reach individual MPs and get them on our side."

Protester Richard Phelps, 65, wore a dustbin with the words Bin The Bomb' on the side.

The civil engineer from Glasgow said: "A short distance from here we have the biggest nuclear arsenal in Europe and my home is just 25 miles away."

Yesterday ministerial aide Jim Devine became the second member of the Government to quit over the Government's plans.

The Livingston MP stepped down as a parliamentary private secretary at the Department of Health.

Deputy Commons leader Nigel Griffiths quit his job on Monday.

The Government - which says the cost of replacing Trident will be up to £20bn - was expected to win the early-evening vote with support from the Conservative party.