- EU-UK post-Brexit trade deal
image copyrightEPAimage captionLord Frost will give an update on the Northern Ireland protocol in Parliament later
The UK is expected to warn the EU it is prepared to unilaterally override the Brexit arrangements for Northern Ireland if a simplified agreement cannot be reached.
The Northern Ireland Protocol helps prevent the need for checks on the island of Ireland's internal border.
But Lord Frost says its implementation is unbalanced and unsustainable.
The Brexit minister will explain the government's proposals in a statement to Parliament later.
The deal was negotiated by Lord Frost but he is expected to say the protocol needs to be radically changed.
However the UK will not be triggering Article 16 of the protocol – which would allow it to suspend parts of the Brexit deal – "in the short term", a government source has said.
Lord Frost is due to give a statement to peers later, while his statement will also be read to MPs in the Commons by Northern Ireland Secretary Brandon Lewis.
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Marks & Spencer has warned there could be higher prices and less choice for its Northern Ireland customers if EU customs rules come into force later this year.
Its chairman Archie Norman said "pointless" checks with the Republic of Ireland were "threatening" to the business.
What is the Northern Ireland Protocol?
The protocol was agreed by the UK and EU in October 2019 and was subject to further negotiation and agreement in 2020.
It helps prevent checks along the land border between Northern Ireland and the Republic of Ireland.
This was easy to do when both Ireland and Northern Ireland were part of the EU, because they automatically shared the same EU rules on trade and no checks were needed on goods travelling from one country to another.
To avoid checks on goods along the Irish border after Brexit, it was agreed some would be carried out when they entered Northern Ireland from England, Scotland or Wales instead.
Inspections take place at Northern Ireland ports, and customs documents have to be filled in.
This has prompted criticism that a new border has effectively been created in the Irish Sea.
Read more here.
The biggest practical difficulty with the protocol concerns the movement of food from Britain to Northern Ireland.
Brussels says that could be solved if the UK agreed to follow EU food standards – known as a Swiss-style deal.
But Lord Frost says the UK is not prepared to concede control over food standards and wants what is known as an equivalence deal – where the EU would accept British standards as being as good as its own.
Appearing in front of Parliament's European Scrutiny Committee on Monday, the Brexit minister said the only way to make the protocol sustainable was to "find a way to hugely reduce or eliminate the barriers between Great Britain and Northern Ireland".
He told MPs the government was keeping "all options on the table" to resolve the issues.
According to the Financial Times newspaper, the Brexit minister will push for an "honesty box" approach, allowing companies to declare their goods are only destined for sale and use in Northern Ireland to exempt them from checks on the Irish Sea border.
Prime Minister Boris Johnson used a phone call on Tuesday with his Dublin counterpart Micheal Martin to call for "pragmatism" to address the "serious challenges that have arisen with the protocol".
A Downing Street spokeswoman said: "The prime minister emphasised that the way the protocol is currently operating is causing significant disruption for the people in Northern Ireland."
Meanwhile, in a press briefing on Tuesday, a spokesman for the US State Department urged the UK and EU to "negotiate within the existing mechanisms when differences arise".