BELFAST, Oct 1 (Reuters) - British Prime Minister Boris Johnson said on Friday that Northern Ireland"s contentious post-Brexit trading arrangements could work in principle if they were "fixed" but warned the EU they would be "ditched" if not. The Northern Ireland protocol was part of the Brexit divorce settlement Johnson negotiated with the European Union. But London has said it must be rewritten less than a year after it came into operation due to the barriers businesses are facing importing goods from Britain. "We hope that we can fix this thing. This is not a problem that we wanted, I have got to stress that. I can"t emphasize that more," Johnson told BBC Northern Ireland. "The protocol could in principle work... It has got enough leeway in the language for it to be applied in a common sense way without creating too many checks down the Irish Sea." But he warned it will come down to "fixing it or ditching it". "What I am saying to you is I want to see a real negotiation. I want to see the EU come to the table with some serious proposals to fix it." Brussels are due to respond in full shortly to a "command paper" put forward by London in July calling for fundamental changes to the protocol. The European Commission has rejected a total renegotiation. read more The July proposals also once again raised the prospect of triggering "Article 16" of the agreement, which allows either side to unilaterally seek to dispense with some of the terms if they are proving unexpectedly harmful. Neither side can scrap the protocol via these safeguard measures. Asked if he would trigger Article 16 as soon as next week, Johnson said it depended on what the EU brings forward and "whether they are willing to negotiate seriously about removing the obstructions that we have currently got."