"This is a decision which is based on our strong view about the sanctity of Australia's gun laws and to ensure that at no stage that those things should ever be put at risk,"Mr Morrison said at a press conference on Thursday morning.
"It is very important - having been the party that introduced those laws - that we ensure that they are forever protected and there can be no compromise when it comes to those issues or any trading on the issue of those gun laws."
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The decision affects Liberal Party preferences only,and does not compel the National Party or all of the Queensland Liberal National Party to place One Nation below Labor.
Queensland LNP members who sit in the Liberal party room in Canberra will have to follow the directive,but those who sit in the Nationals party room will not.
"What the Nationals do is a matter for them,that's a separate issue,"Mr Morrison said.
Deputy Prime Minister Michael McCormack said the Nationals had not made a decision on preferences.