The imposition of a customs frontier on the Irish border would "play fast and loose" with both the economy and peace process, Sinn Fein has warned.
The republican party dismissed any suggestion trade movement between Northern Ireland and the Irish Republic could be monitored by technology as "nonsense and impossible to deliver".
The UK government's vision of how its only land border with the EU will operate when it exits the Union will be outlined in a much-anticipated document on Wednesday.
There are more than 200 roads crossing the Irish border.
Critics of a technology-based solution, potentially involving CCTV cameras and number plate recognition systems, question how movement between the jurisdictions could ever be tracked without causing major disruption.
The Irish government has made clear its position that technology alone will not resolve the border conundrum.
David Cullinane TD, Sinn Fein's spokesman on Brexit, said: "It is clear that the British Tory party are in disarray over Brexit.
"They have no plan, no solutions for Brexit, only slogans."
He added: "The notion of a frictionless technological border has been dismissed as nonsense and impossible to deliver.
"What is clear is that Tories are prepared to use Ireland as collateral damage in their negotiations with the EU.
"What we need is a real solution that works for our economy, our communities, and delivers for all Ireland."
However, Democratic Unionist MP Sir Jeffrey Donaldson insisted only the main arterial routes needed to be monitored.
"If people want to export their goods they have to go through the proper process and clearly most of the cross border roads aren't used for trade purposes, they are used on a daily basis by local people," he told the BBC.
"It is the main roads that are used for haulage and trading.
"So we are confident that we can deal with this in a pragmatic way."
On Sunday, SDLP Leader Colum Eastwood accused the UK government of drawing up its border plan on the "back of an envelope".
"It is almost laughable that it took the British Government over a year to come up with it," he said.
"Anyone who knows anything about the Irish border knows it's a non-runner."
He added: "Any border must be around the island of Ireland, not across it.
"This is the only position which recognises our unique circumstances and it is the only position which is actually enforceable.
"It is the only serious and credible solution to the Brexit problem which has so far been proposed."
Meanwhile, Ulster Unionist leader Robin Swann has urged the Dublin government to kill off any suggestion that a customs border could be imposed in the Irish Sea, around the island rather than dividing it.
Taoiseach Leo Varadkar has already said the proposal is not one he is tabling as a potential alternative.
Mr Swann called on him to go further.
"If he has any respect for the people of Northern Ireland, Leo Varadkar must come out and dismiss the idea of a post-Brexit border in the Irish Sea once and for all," he said.
Mr Swann repeated his concern that the Brexit issue was being pursued by republicans and nationalists to advance a united Ireland.
"Brexit negotiations should not be used as a Trojan Horse by those who seek to exploit the situation to further their united Ireland agenda," he said.
A spokesman for the Irish Government said it welcomed indications that the UK is providing "more clarity on its thinking".
He said the position paper on future EU-UK customs arrangements will be analysed in detail and will need careful consideration.
The Government said the immediate focus of negotiations would be on issues including citizens' rights, the financial settlement and Irish specific issues.
"In this regard, the Government welcomes the UK's intention to publish a second position paper, on Northern Ireland and Ireland specific issues, later this week," the spokesman said.
"Once sufficient progress has been made on these phase one issues, we will be in a position to commence phase two of the negotiations, where parallel discussions will take place with the UK on future relationship issues, including customs."
Chancellor Philip Hammond has been accused of caving in to hard line Cabinet Brexiteers after accepting Britain will withdraw from the European single market and the customs union when it leaves the EU in 20 months' time.