The Government has denied misleading Northern Ireland politicians over customs checks post-Brexit.
Northern Ireland spokesman Viscount Younger of Leckie said there would be "unfettered access" for Northern Ireland businesses to the UK market.
But he acknowledged there would be requirements for live animal and agrifoods checks.
Former Ulster Unionist leader Lord Empey had asked the Government whether customs posts would be established in Northern Ireland from next year and how this was compatible with assurances on free access.
Lord Younger said the protocol was a "practical solution to prevent a hard border on the island of Ireland" and made clear that Northern Ireland "remains an integral part of the UK and its internal market".
This included legislating to guarantee "unfettered access for Northern Ireland businesses to the UK market".
In a virtual Lords urgent question, Lord Empey said ministers had repeatedly assured Parliament there would be no checks on goods to or from Northern Ireland, adding: "There is a widespread feeling that members have been consistently misled."
Lord Younger said: "We've always been clear that there will be requirements for live animal checks and agrifoods, building on what already happens at Larne and Belfast."
He added that ministers wanted to work with businesses here and the Executive to ensure "new administrative procedures are streamlined and efficient". The Government wanted to ensure "optimum flow of trade".
Former Labour NI secretary Lord Reid of Cardowan warned that a "clear breach of a vow given by ministers" undermined trust in the Government. Lord Younger said he was not sure what the breach was, adding: "We have always said there will need to be light-touch checks particularly for live animal checks and agrifoods coming from the internal markets in the UK across to Northern Ireland."