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EPA
The Brexit Secretary David Davis is visiting Northern Ireland as part of the government's work on future customs arrangements with the EU after Brexit.
Mr Davis made the trip alongside the Business Secretary Greg Clark.
On Sunday, both men joined the Secretary of State, Karen Bradley, in meetings with cross-border companies.
Mr Davis previously faced criticism from Sinn Féin after he made an unannounced visit to the border region in County Armagh in April.
During that visit Mr Davis did not follow the protocol of telling the local MP that he would be in the constituency, and he later apologised.
'Maximum facilitation'
One group is considering a "customs partnership" whereby the UK would collect tariffs on behalf of the EU - but without the need for new border checks.
Meanwhile, Mr Davis' group is looking at "maximum facilitation" - a solution based on using technology to minimise the need for customs checks after Brexit