A former Stormont employment minister has accused the First Minister of preaching fantasy economics over Brexit.
Arlene Foster described the leave vote as presenting the biggest economic opportunity for the UK in decades.
She was addressing her first DUP annual conference as leader on Saturday.
The Alliance Party's Stephen Farry said: "This type of rhetoric reflects fantasy economics and it is frankly disturbing that the First Minister is articulating this.
"It is one thing to call for people to respect the Brexit referendum, but it is an entirely different matter to pretend that this opens up a new world of milk and honey.
"The essence of the Brexit vote was about prioritising control of borders, restricting immigration, and trying to recapture some long-since expired notion of sovereignty in a globalised world at the expense of economic interests.
"Brexit is a massive self-inflicted economic wound."
He said the overall UK economy has already shrunk in size, and experts were reassessing the prospects of long-term economic growth.
"Whatever trading outcome emerges will inevitably bring some form of obstacles or barrier to Northern Ireland companies doing business.
"Despite the good work of many people over the past few years, the Northern Ireland economy remains structurally weaker than the UK as a whole. And the UK itself continues to have several disadvantages relative to its competitors, in areas such as productivity.
"The tragedy of Brexit, is that it comes at a time when the local economy was on the brink of a real lift-off. Now, with uncertainty over market access, it is going to be more difficult to attract investment."
The DUP campaigned for a leave vote in the June referendum.
Mrs Foster said that she respected those who wanted to remain but insisted it was time to move on.
"That debate is over. Rather than talking up the challenges, we should be looking forward to the opportunities.
"Brexit represents the biggest economic opportunity for this country in decades.
"But, the only way we can ensure that Northern Ireland's interests are best served is if we are united and determined."