Irish Prime Minister Leo Vardakar has ruled out suggestions that those crossing the Irish border after Brexit might need to pre-register.
The taoiseach was reacting to reports that this was one idea being considered by the UK government.
"It is not a solution that we envisage," he told an audience in Austin, Texas.
The future operation of the Irish border has been a sticking point in the negotiations between the UK and the EU.
Both sides have said they want to avoid a so-called hard border - the installation of physical barriers and customs checkpoints - between Northern Ireland and the Republic of Ireland.
The idea of pre-registration has come from a report by a customs expert which was prepared for the European Parliament.
One potential solution put forward in the Smart Border 2.0 report is that people crossing the border after Brexit would have to register in advance to avoid checks and delays.
However, Mr Varadkar dismissed it, adding that it might be helpful if British senior cabinet officials such as Boris Johnson and David Davis visited the border to see first hand that it was "invisible".
The UK government has guaranteed there will be no hard border but it is not yet clear how that can be achieved