A leading Westminster think tank has criticised Irish prime minister Leo Varadkar for taking a tougher line on post-Brexit Irish border controls.
Taoiseach Varadkar is reported to want customs and immigration checks at airports and ports, instead of a softer electronic border.
Policy Exchange's chief economic adviser Graham Gudgin said: "This new tough line from Dublin on the Irish border is an unhelpful change of direction on an already complex issue. The Taoiseach's decision to cease work on a potential electronic border is particularly unwelcome."
The DUP has responded to hardening sentiment from Dublin by promising to leverage its alliance with the Conservatives. It believes pushing the border to the Irish Sea could undermine the Northern Irish peace process.
Gudgin, a former special adviser to Northern Ireland's first minister. added:
Varadkar’s call last week for the border to be moved to the Irish Sea is incoherent, is said not to have been checked with his own foreign affairs officials, and was not mentioned in his speech in Belfast on Friday. Hopefully this is the last we will hear of it.
He continued: "His latest call in Belfast for the UK to negotiate a bespoke customs unions deal with the EU would require a special dispensation from the EU to allow the UK to agree new trade deals with third countries. This would be a major departure from EU practice and is unlikely to be agreed."