secret police
From Longman Dictionary of Contemporary Englishsecret policeˌsecret poˈlice noun → the secret policeExamples from the Corpussecret police• With no worries of visits from secret police, we laughed and joked the night away, drinking wine and plum brandy.• We even have our own secret police.• And that would get us back to castor oil and the secret police.• Till now Oufkir had controlled the secret police and pursued the kings enemies ruthlessly.• Apart from recommending free elections, the discussion group also demanded that the secret police should be dissolved.• What are you, secret police?