Students from Durham University have joined a river-side search for missing Luke Pearce, 19.
He has not been seen since a night out with friends in the city on Saturday night.
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Durham Police say four women and one man have been arrested and two people remain up a tree at the Pont Valley opencast demonstration.
Durham Constabulary have called in a specialist climbing team to help remove protesters at the Pont Valley site.
Residents of a 495-property housing estate in Newton Aycliffe are split over proposals to demolish and rebuild the site.