Drones to monitor Northern Ireland's post-Brexit border with the Republic is a proposal apparently under consideration by ministers, according to Ed Miliband.
The former Labour leader said he had heard the idea was floated at last month's Chequers summit involving Cabinet ministers and Prime Minister Theresa May.
Mr Miliband labelled it "ridiculous" to use an "eye in the sky" to ensure the European Union customs union, which allows countries within it to trade more freely with each other, is not breached.
MPs on the Northern Ireland Affairs Committee are to investigate whether Northern Ireland should have a special status in a post-Brexit UK and what changes to visa controls might be needed.
James Brokenshire, the Northern Ireland Secretary, has said he does not want to see a return to the "borders of the past" in relation to Northern Ireland and the Republic of Ireland.
Speaking at a fringe event to the Labour Party conference in Liverpool, Mr Miliband said his understanding of the Chequers meeting was based on a second-hand account.
He said: "The best solution they could come up with, which the Treasury was sent away to look at, was some sort of eye in the sky to see whether people were breaching the customs union and the single-market.
"Now, I know we're all in favour of science and technology - drones - but it sounds like a sort of ridiculous solution.
"But I think it's incredibly important... that we don't go back to our hard border and that absolutely should be among the criteria that we set for these negotiations."
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