Cleveland Police are investigating after beach cleaners discovered what could be a grenade at Seaton Carew beach.
Bomb disposal teams from Catterick Garrison are on the way to the scene.
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The threat level has been raised to critical by MI5's Counter-Terrorism Analysis Centre.
Prime Minister Theresa May announced the decision from Downing Street.
Newcastle Central Mosque is welcoming Muslims and non-Muslims alike this evening to stand in solidarity with the people of Manchester.