verb

state that one refuses to admit the truth or existence of.

both firms deny any responsibility for the tragedy

contradict,repudiate,gainsay,declare untrue,dissent from,disagree with,challenge,contest,oppose,retract,take back,back-pedal,disprove,debunk,explode,discredit,refute,rebut,invalidate,negate,nullify,quash,shoot full of holes,shoot down (in flames),disaffirm,controvert,confute,negative