The UK government is confident of agreeing changes to the Northern Ireland Protocol with the European Union, MPs have been told.
Northern Ireland Secretary Brandon Lewis said there "has to be" alterations to the arrangement, which is a key part of the Brexit deal struck between London and Brussels designed to avoid a hard border on the island of Ireland.
"The current status quo is not sustainable," he told the Northern Ireland Affairs Committee.
The row over the Protocol has soured ties between the two sides in recent months and provoked protests in Northern Ireland.
Lord Frost, the Brexit minister, has complained that it is having a "chilling effect" on trade between Great Britain and Northern Ireland.
As part of the arrangement, Northern Ireland remains under some EU rules and there are checks on goods entering Northern Ireland from Great Britain.
Mr Lewis' comments come after Edwin Poots, the outgoing leader of the Democratic Unionist Party, said he had been given a personal assurance from the UK government that there would be significant alterations to the Protocol.
Asked what he had told Mr Poots, Mr Lewis said: "We are very clear that the current position of the Protocol is not sustainable, it is causing issues for businesses and consumers and citizens in Northern Ireland, and we need to rectify that.
"Ultimately, for us there is a very core point about the Protocol, which is about protecting and respecting the UK's internal market and not disrupting everyday lives of people in communities.
"We want to get that rectified and we are determined to do so, so I think it is reasonable for anybody to take the view that we have said that there will be changes because there has to be, the current status quo is not sustainable."
The Northern Ireland Secretary's remarks echo comments from Brexit minister Lord Frost to MPs on Tuesday.
He said the UK government has not "made a secret of the fact that we find it hard to see how, as currently operated, important elements of the Protocol are sustainable".
He told the Commons Foreign Affairs Committee that the UK was "considering all our options".
Lord Frost said progress was being made in some areas, in particular on extending the grace period on chilled meats such as sausages and mince, which expires at the end of the month.
Boris Johnson told Sky News earlier this month he is willing to "do whatever it takes" to tackle the issues caused by the Protocol.