The Government's latest intervention on Brexit is motivated by politicking for domestic purposes, the DUP claimed.
Nigel Dodds insisted Dublin was positioning for a general election after Taoiseach Leo Varadkar said Ireland will not help Britain design an economic border for Brexiteers.
The Government is unconvinced by the UK's plans to use technology to maintain the invisible land border between the North and Ireland.
The DUP deputy leader said: "All of this can hardly be put down to inexperience. Rather, it seems to be deliberate positioning by the new team at the helm in Dublin in preparation and positioning for a coming general election.
"Dressed up as grand ideas, what's going on is pure politicking for their own domestic market. Let no one pretend otherwise.
"It's simply taking things backwards at a time when common sense co-operation between our two countries and between the Republic and Northern Ireland is what's needed."
Mr Dodds said there was already an economic border between the North and Ireland.
"For instance, does he (Mr Varadkar) not realise that every time you cross the border, you need to change currency?
"Or that each jurisdiction is subject to entirely different taxation and financial regimes?
"Since Enda Kenny and Charlie Flanagan departed the scene, confusion seems to be the order of the day."
Mr Varadkar also said he would try to find solutions that would "minimise the damage" to relations between Britain and Ireland, to the peace process and to trading links.
The Times newspaper prompted the exchange after suggesting the Ireland's preferred option for a post-Brexit frontier was for customs and immigration checks to be located at ports and airports instead of on land.
Foreign Affairs Minister Simon Coveney told RTE: "There is no proposal that is suggesting that there be a border in the Irish Sea."