DAVID Davis's department has insisted the Brexit secretary takes his parliamentary commitments "extremely seriously" after the senior Tory declined an invitation to appear before an influential Westminster committee.
Mr Davis turned down the opportunity to answer questions about the border from the cross-party Northern Ireland Affairs Committee.
The committee chairman described the decision as "disappointing" at a time when the future status of the Irish border has emerged as one of the major stumbling blocks to agreement on Britain's EU withdrawal.
The MPs had invited the Brexit secretary to update them on the British government's proposals to deliver a frictionless border.
In a letter to committee chairman Andrew Murrison, Mr Davis said he had already answered questions about the north during appearances before other Westminster committees in the Commons and the Lords.
He offered to send junior ministers from the Department for Exiting the EU (DExEU) and the Northern Ireland Office in his place, while agreeing to answer any "outstanding questions" in writing.
Dr Murrison said: "My committee is most disappointed that David Davis has turned down our invitation to give evidence.
"Michel Barnier has given us oral evidence as EU negotiator and the committee felt it would be reasonable to ask his UK counterpart Mr Davis to do the same."
Dr Murrison said the Northern Ireland and the border represented an "absolutely pivotal element of the Brexit process".
"This is more urgent now as a technical solution to the border is one of two options cited by ministers.
"Given the committee's caution over the prospects for a technical solution in its original report on the Irish land border post Brexit, we wanted to give the minister an opportunity to say what progress had been made.
"We would then be happy to update our report if warranted by evidence received.
"Otherwise, clearly, we cannot and the opinion expressed in the original report will have to stand."
A DExEU spokesman said Mr Davis took his parliamentary commitments "extremely seriously".
"Our policy is clear – we are committed to ensuring there is no hard border between Northern Ireland and Ireland and to ensuring the same unfettered access for Northern Ireland's businesses to the whole of the UK's internal market," he said.
"We have set out our preferred customs models to enable trade to remain as frictionless as possible."
