Karen Bradley has promised to seek the best Brexit deal for Northern Ireland after meetings with businesses there about the Irish border.
The Northern Ireland Secretary visited a cement factory in Co Fermanagh and the chief executives of local authorities which adjoin the border.
On Sunday her British Brexit and Business Secretary colleagues David Davis and Greg Clark joined her in Belfast for meetings with 14 organisations as they explored a technological solution to cross-border trade to minimise the need for customs checks after the divorce.
The potential impact of regulatory differences on North-South commerce in Ireland is central to negotiations on a pact ahead of next year's withdrawal from the EU.
Ms Bradley said: "The thing I need to do is get on and do the job to make sure that we get the right Brexit, the right deal for the people of Northern Ireland and that we continue to build on the United Kingdom and all that we do as a united country."
The British Prime Minister has split her ministers into two teams as they work towards a reconciliation on how to manage arrangements with the EU after the exit.
Ms Bradley, Mr Davis and Mr Clark are part of a group considering "maximum facilitation", a solution based on using technology to minimise the need for customs checks after Brexit.
Ms Bradley said: "This is really so that I can test how maximum facilitation could be made to work and whether it can be made to work for Northern Ireland."
She said she had been presented with lots of ideas and thoughts.
"My job as Secretary of State for Northern Ireland is how do we get it right for Northern Ireland."
Another group established by the British Prime Minister, featuring Brexiteers Liam Fox, Michael Gove and Remain-backing Cabinet Office minister David Lidington, is considering a "customs partnership" whereby the UK would collect tariffs on behalf of the EU without the need for new border checks.
The UK's Brexit Department has said both customs models under consideration are designed to meet the UK's three guiding principles: allowing it to trade goods and services as freely as possible with the EU, enable it to have an independent trade policy, and avoiding any hard border between Northern Ireland and the Republic of Ireland while maintaining the constitutional and economic integrity of the United Kingdom.