The Police Service Northern Ireland believe the reinforcements will be required to deal with 'disorder' in the event of a no-deal Brexit, which could see Britain chaotically fall out of the European Union at the end of March.

Internal disarray within the Conservative Party as it clings to power with the support of the unionist DUP means that a negotiated agreement on Brexit appears increasingly unlikely.

The transfer of police from English forces and Police Scotland is expected to begin this month. It was previously announced that the the PSNI has been allocated an additional special funding so that it can construct new bases and recruit more than 300 additional staff to prepare for Brexit.

The prospect of large numbers of untrained British riot police being deployed across the North would be the clearest sign yet that the 1998 Good Friday peace Agreement is in crisis.

Despite the success of the British Prime Minister Theresa May in brokering a withdrawal agreement with the EU and the Dublin government, the DUP and their unionist Tory supporters have insisted on a more uncompromising deal which would ensure a hard border and help reinforce the partition of Ireland.

Negotiations with the EU have concluded, and the Irish Taoiseach, Leo Varadkar, has said Ireland is "now preparing for no deal with the same level of seriousness that we would" an agreed Brexit.

The DUP's has Nigel Dodds claimed the preparations for a hard border are "nonsense propaganda". Jacob Rees-Mogg, a leading Tory who has refused to vote for Theresa May's withdrawal deal in the House of Commons, and was the ringleader of a failed attempt to oust May through a vote of no confidence in December, has also dismissed the Irish border as a "phantom" concern.

"If we leave without a deal the main culprit will be the obdurate Irish government's threats about the phantom border issue," he wrote on Twitter. However, Rees-Mogg has also warned that Irish citizens should be subject to "inspection" if they attempt to cross the border following Brexit.

"There would be our ability, as we had during The Troubles, to have people inspected," he said. "It's not a border that everyone has to go through every day."