Hilary Benn has mocked the idea of "tethered zeppelins" monitoring the Irish border after Brexit.
The Labour Party MP and Brexit Select Committee chair dismissed a think tank's suggestion that "persistent surveillance of the border region" could be achieved through patrols by unmanned aerial vehicles.
Mr Benn said the suggestion stemmed from the British government's "impossible" position of wanting no border and yet to leave the single market and customs union.
He added: "Now when it's pointed out to them that's a bit of a problem ministers say 'ah well technology will come to our rescue' even though their ideas are untested.
"One organisation actually suggested that maybe airships and drones could hover above a non-existent border.
"Now I hate to say this, but I don't think that tethered zeppelins or airships are going to deal with the problem in Northern Ireland.
"The truth is whatever the weather, however much the Government spends, it is very hard to see, if not impossible, how the two things can be reconciled if we're going to avoid the return to a hard border.
"That is why there's a crisis in the negotiations with EU - that is why the Irish Government is pushing so hard."
The Legatum Institute's paper on aerial monitoring is thought to echo the view of Brexit Secretary David Davis, in that a hard border can be avoided through a combination of technology and a comprehensive trade deal.