The DUP is not prepared to be taken for "fools" over the Northern Ireland Protocol, a party MP has said.
Gregory Campbell was speaking ahead of the resumption of post-Brexit technical level talks between UK and EU officials this week.
The DUP is refusing to re-enter government until the Northern Ireland protocol bill – which scraps part of the Brexit agreement – is through parliament.
Mr Campbell said only time will tell if the apparent change in tone between Westminster and the EU will amount to anything.
"Liz Truss can tell us until she's blue in the face that she means what she says, but we'll believe it when we see it, in writing, in legislation, being enacted in the House of Commons, and not before," he said.
Earlier this week, Steve Baker, Minister of State at the Northern Ireland Office, apologised for failing to understand Irish concerns during previous Brexit talks.
“I recognise in my own determination and struggle to get the UK out of the European Union that I caused a great deal of inconvenience and pain and difficulty,” Baker said on RTÉ Radio. “Some of our actions were not very respectful of Ireland’s legitimate interests. And I want to put that right.”
Taoiseach Micheál Martin described the comments as "honest" and "very helpful".
However, The Irish Times reported that the Government remains sceptical about Britain taking a new approach to negotiations on the protocol ahead of the talk this week.
Last month, Mr Campbell said that linking the number of Catholics and Protestants in Northern Ireland with the prospect of a Border poll is "lazy analysis".
The MP said writers and politicians using a "religious headcount" to speculate about a united Ireland referendum "should step back" and examine electoral outcomes over the last two decades.
His comments came before of the release of the 2021 Northern Ireland census, which revealed that there are now more Catholics that Protestant living in Northern Ireland.