Security high in Ireland hours before Queen's visit

The Queen is due to begin the first visit to the Republic of Ireland by a British monarch, amid a massive security operation.

It is being hailed as a milestone in Anglo-Irish relations, but the visit also comes at a time of increasing sectarian violence in Northern Ireland.

It has meant the biggest security operation seen in Ireland is being mounted for the visit, amid concern dissident republicans could try to disrupt events.

Mark Simpson reports from Dublin.