Northern Ireland Police Federation chairman Terry Spence, who represents rank and file officers, praised his "brave" colleagues on their find.
He said the weapons were "undoubtedly intended to murder officers" and that there is "hiding place for terrorists".
More top news
Demonstrators jumped the barrier and lay down on the red carpet to draw attention to cuts to domestic abuse services.
Doctors in Australia have reattached 16-month-old Jaxon Taylor's head to his spine after he was 'internally decapitated' in a car accident.
Alan Titchmarsh becomes the new chancellor at the university where I and my daughter both studied, writes Alastair Stewart.