Mr Morrison said his decision was"based on our strong view about the sanctity of Australia's gun laws".
Pauline Hanson was captured on a hidden camera saying she had read a book about Port Arthur and there were a"lot of questions there".
One Nation's WA leader Colin Tincknell has delivered a stinging rebuke to two of the party's east coast operatives.
The Prime Minister said the right-wing minor party was not the answer for voters frustrated about immigration,employment and the drought.
"This is the stuff you see in James Bond magazines. I would never expect you would see this for real in the real world."
Queensland One Nation leader Steve Dickson,discussing how it could use money given to the party by a US pro-gun lobby group,said:"you'd have the whole government by the balls."
A journalist,posing as the head of a fake gun lobby group,secretly filmed Pauline Hanson's top adviser trying to raise money from US pro-gun groups.
Senate president Scott Ryan says video footage showed"inappropriate behaviour of a pass-holder towards a senator".
The Senate president will examine last night's events,as Senator Brian Burston denies allegations he smeared blood on Pauline Hanson's office door.
Two parties hoping to lure conservative voters away from the Morrison government are locked in a bitter rivalry.
Despite Hanson's insistence she’s the boss,her devolution of a large slice of her control to a succession of male lieutenants is an unbreakable pattern.