Brexit Secretary David Davis has made another visit to Northern Ireland.
On Sunday his department said he had returned as part of a "fact-finding" mission alongside Northern Ireland Secretary Karen Bradley and Business Secretary Greg Clark.
It did not say where he intended to visit and only that he would be meeting with representatives from the freight industry, cross-border business and community stakeholders "to further explore how the highly-streamlined customs model could address the unique circumstances of Northern Ireland".
The SDLP said it did not come as a surprise to hear of the visit through news reports.
"It is clear for everyone to see Mr Davis doesn’t want to engage with politicians who will put the hard questions to him on his Government's failure to protect the interests of citizens here.
“Mr Davis would clearly rather sneak about and bury his head in his sand while taking his political lead on the politics of this island from only the DUP. Our door is open when the Tory politician decides he actually wants to be responsible and step up to engage at a political level across the political spectrum here.”
Responding, DUP MP Ian Paisley said: "It was so secret he met with a dozen senior business people and organisations in NI. SDLP feel left out because they have nothing positive to contribute. The government is going over the heads of the SDLP to the people and SDLP don’t like it."
Later pictures were issued to the media of Mr Davis meeting with business representatives at Stormont. Businesses represented included the MJM Group, Diageo and NuPrint. While Derry City and Strabane Council was represented along with the Londonderry Chamber of Commerce. The Freight Association, WS Dennison, Surefreight and BP McKeefrey also attended meeting with the ministers of state.
Secretary of State Karen Bradley said discussions were constructive and brought to life the unique circumstances of Northern Ireland.
The Department for Exiting the EU said the visit was part of the "max fac" working group exploring potential future customs arrangements, focusing on using technology to overcome the difficulties around what will become a land border with the EU as well as maintaining the pledges made by government of avoiding having additional infrastructure.
A statement said: "The Prime Minister has tasked two working groups from the European Union Exit and Trade (Strategy and Negotiations) sub-committee with exploring further the two possible future customs arrangements the UK Government have set out.
"Both of the customs models currently under consideration are designed to meet the UK’s three guiding principles: allowing us to trade goods and services as freely as possible with the EU, enable us to have an independent trade policy, and avoiding any hard border between Northern Ireland and Ireland while maintaining the constitutional and economic integrity of the United Kingdom."
Asked for further details, a department spokeswoman said they had nothing further to add to the statement. They are not expected to meet the media.
Mr Davis faced criticism for not following protocol on his visit to the border in April. As well as political representatives including the DUP the media was not informed of the visit.
His department apologised for what it described as a "administrative oversight" in not notifying Sinn Fein MP Mickey Brady of the visit as is normal procedure.
The "maximum facilitation" option is under consideration by the British Government as it tries to find a solution to the Irish border post-Brexit.
The option - favoured by Brexiteers - would see the UK leave the customs union but use technology to minimise customs checks and physical infrastructure along the border. The UK would set tariffs on goods entering the UK but products destined for the EU would be exempt and could travel in bond.
The second option under consideration is a customs partnership.
This would see the UK effectively remain in the EU’s customs area but be able to strike free trade deals. The UK would collect EU tariffs on goods entering Britain and abide by EU procedures.
Theresa May has split her Cabinet into two groups to examine the options and come up with proposals on how they could work.