Industrial action at the Faslane and Coulport naval bases is likely to affect some operations of the Trident nuclear submarines, the BBC has learned.

Naval dockyard workers at the bases in Scotland voted in favour of strike action over plans to move their jobs into the private sector.

The Royal Navy insisted there was no question of action compromising Britain's nuclear deterrent.

But the BBC has learned Friday's one-day strike coincides with the scheduled re-arming of one of the Trident missile submarines.

Pay fears

HMS Vengeance is the only currently operational Trident submarine, and unless its itinerary is changed it could be caught up in the industrial action.

The general impact of Friday's strikes is not likely to be huge, but the unions have insisted they will continue.

Leaders fear hundreds of workers may be made redundant and others will face cuts in pay and conditions.

They say this breaches a direct promise made to them by Defence Secretary Geoff Hoon.

Modernisation plan

David Luxton, national secretary for the white-collar union Prospect, said there was "overwhelming support" for strike action.

The UK Government has warned that job losses could be as many as 750 if Devonport and Portsmouth in England are included.

Ministers warned that the majority of redundancies could occur in Scotland but said the changes are necessary to modernise the service and will save taxpayers more than �300m over the next five years.

The defence unions plan to hold mass meetings in Portsmouth and Devonport next week and plan to meet Mr Hoon on Wednesday.