Northern Ireland's Agriculture Minister has halted construction of permanent inspection facilities for post-Brexit checks on agri-food goods arriving from Britain.
DUP minister Gordon Lyons has also stopped further recruitment of inspection staff for the port facilities and ordered an end to charges levied at the ports on traders bringing goods from Britain into Northern Ireland.
Ongoing Irish Sea trade checks, which are taking place at existing repurposed port buildings and other temporary facilities, will continue.
Mr Lyons' decision relates to ongoing work on new purpose-built inspection facilities at ports such as Belfast and Larne.
Mr Lyons told the PA news agency: "I've just let executive colleagues know that today I instructed my department to halt work on a range of issues relating to work at the ports.
"This is in and around a number of areas, first of all further infrastructure, any further infrastructure builds; the additional recruitment of staff; and also the charging at the ports."
The decisions come amid the ongoing controversy over disruption caused by the Northern Ireland Protocol, which governs Irish Sea trade post-Brexit.
Unionists are angry at the protocol's requirement for checks on many goods entering Northern Ireland from the rest of the UK.
They claim it has driven an economic wedge between it and Britain, and has undermined the union as a result.
Mr Lyons said his move was in response to the "practical difficulties" caused by the protocol.
He cited uncertainty over the movement of goods when grace periods currently limiting protocol bureaucracy end at the start of April.
He said: "We don't know what the movement of retail goods from Great Britain into Northern Ireland is going to look like, we don't have the support in place through the digital assistance scheme yet either, and all of the SPS (sanitary and phytosanitary) issues around the end of the grace period are just so uncertain and it's real nightmare for us and it's going to be causing us an awful lot of problems."
Previously, when the former DAERA Minister took a similar stance, his Permanent Secretary took forward the Executives responsibilities. The Protocol is a consequence of Brexit. The DUP championed Brexit & must own the consequences. Business and society need certainty, not stunts.— Michelle O'Neill (@moneillsf) February 26, 2021
Responding to the move, Northern Ireland Deputy First Minister Michelle O'Neill said that the DUP "championed Brexit and must own the consequences".
In a tweet, Ms O’Neill said the Northern Ireland Protocol was a consequence of Brexit, and that businesses and society "need certainty, not stunts".
SDLP leader Colum Eastwood said that the DUP "cannot pick and choose" which duties and obligations of Executive leadership it wants to adhere to.
Party deputy leader Nichola Mallon has requested an emergency meeting of the Stormont Executive, as the move cannot be put into effect with Executive agreement.
"Over the course of the last few months, the SDLP has been working hard to resolve the challenges faced by businesses as a result of post-Brexit changes to trading relationships," Mr Eastwood said.
He added: "We have put our shoulders to the wheel to explore new opportunities and maximise the benefits of the new settlement. We have done so in a spirit of cooperation and partnership.
"It is deeply concerning that DUP ministers are actively trying to sabotage the arrangements and inject further uncertainty into a difficult situation for local businesses to suit their own narrow political interests."