Brexit Secretary David Davis has again been urged to visit the Irish border amid warnings that any form of infrastructure impeding movement between the two parts of the island would be "catastrophic".
It emerged this week that Mr Davis has not visited the border for two decades – and his officials confirmed yesterday that he has no immediate plans to experience the frictionless frontier for himself.
During his trip to the US, Taoiseach Leo Varadkar challenged Mr Davis and Foreign Secretary Boris Johnson to follow the example of Secretary of State Karen Bradley, who has already visited the border.
The Brexit secretary has simply indicated that he will visit the border "when the time arises".
South Armagh-born Labour MP Conor McGinn said it was "incredible" that senior British government figures leading the Brexit negotiations had not paid a visit to the border.
"It's hard to overstate just how important it is for them to see the border – or rather the complete absence of one – with their own eyes," he said.
"Then they might realise how catastrophic it would be to have any infrastructure or hardening of it for people living in border communities, for the all-island economy and for wider British-Irish relations."
SDLP Brexit spokeswoman Claire Hanna said it was becoming "tiresome" listening to the likes of Messrs Johnston and Davis making "unworkable" suggestions about how the border would operate after Brexit without having been there.
"Before pontificating any further, they should make the journey to the border, see how it operates, speak to people affected and then maybe they’ll have some sense of the scale of the challenge facing us all," she said.
Meanwhile, the South Belfast MLA has said a Northern Ireland Affairs Committee report published yesterday demonstrated the need for alignment with the EU single market and Customs Union to avoid a hard border.
The MPs' report criticised the British government for its failure to come up with solutions for keeping the Irish border free-flowing after Brexit.
The committee found that any additional infrastructure at the border would not only be "politically objectional but highly ineffective and unworkable".
"That is a stinging indictment of the current UK government’s proposals to date which have been utterly threadbare," Ms Hanna said.
"The report also notes the need for continued alignment with the rules of the European Single Market and Customs Union to prevent a hard border through a two-year implementation period, during which they suggest officials should continue working together to resolve the border challenge."
DUP MP and committee member Gregory Campbell said the report highlighted a need for "continued work" to overcome the vexed issue of the border.
"There is also a need for ongoing work, particularly by the European Union, on the ways in which business and goods will move across the border," the East Derry MP said.
"It is noted that a no-deal scenario would have negative consequences – these would of course be most severe for the Republic of Ireland and it highlights why this should be focused upon by all sides."
Sinn Féin MP Chris Hazzard said the report showed onus was on the British government to bring forward "credible proposals on Brexit".
"This Westminster select committee is now echoing the concerns of many and what we have been saying all along that the British government is still totally unprepared for Brexit and has not put forward any credible or workable proposals to date," he said.
"That is the message we have been hearing in our engagements with MPs from a range of parties."
