Britain plans to use points of entry in the Irish Republic as its front line in combating illegal immigration, according to a report.
London wants to beef up controls at Ireland's ports and airports in order to avoid the return of a "hard border" with Northern Ireland, The Guardian reports.
With Britain and Ireland making use of a common travel area (CTA) since the 20s, the Brexit vote threw up big problems as any return to a "hard" border could contravene the Good Friday Agreement.
Northern Ireland Secretary James Brokenshire told The Guardian that Ireland's external borders would be strengthened in order to help fight unwanted migration once the UK leaves the EU.
"Our focus is to strengthen the external border of the common travel area, building on the strong collaboration with our Irish partners," he told The Guardian.
"We are already working closely with the Irish government and other members of the common travel area to prevent people from seeking to evade UK immigration controls from entering via another part of the CTA.
"There is a high level of collaboration on a joint programme of work.
"This includes investment in border procedures; increased data sharing to inform immigration and border security decisions; passenger data systems enabling the collection and processing of advance passenger information; and harmonised visa processes," he said.
Attempts to use Irish entry ports as the front line of British immigration controls could prove highly controversial in the Republic.