The British government has been criticised for making contradictory remarks about checks on goods moving between Northern Ireland and Britain after Brexit.
Home Secretary Priti Patel was unable to clarify what checks will take place and was not able to rule out the involvement of Border Force officers when she appeared before the Home Affairs Select Committee.
Ms Patel has since written to the committee to clarify the position within the Northern Ireland Protocol, confirming that administrative procedures including a declaration will be required when goods move from Britain to Northern Ireland.
Committee chairwoman Yvette Cooper said: "In the last three days, different senior members of the government have said contradictory things about checks on goods moving from Northern Ireland to Great Britain and the other way round.
"This is too important to be fudged. They need to be straight with people about what checks there will be.
"From the home secretary's letter, it is clear now that there will be checks on goods from Great Britain to Northern Ireland - but why could she and the Home Office not be clear about that yesterday at the committee? Those checks will have a significant impact on Northern Ireland.
"This makes it even more serious that the prime minister is trying to avoid scrutiny - both from the Liaison Committee and for his legislation in Parliament. You can't hide something as important as this."
In written evidence, sent to the committee overnight after her appearance on Wednesday, Ms Patel said on the issue of goods moving from GB to Northern Ireland: "For the protection of the single regulatory zone and consumers on the island of Ireland, and to ensure that the correct tariffs are applied, we will need information on goods moving from Great Britain to Northern Ireland.
"Therefore, administrative procedures including a declaration will be required, which can be completed online."
On goods moving from Northern Ireland to GB, she wrote: "This deal explicitly allows the UK to ensure unfettered market access for goods moving from Northern Ireland to Great Britain.
"The UK does not therefore intend to carry out checks on such movements of goods. There will be a minimal administrative process which is designed to prevent, for example, trade in endangered species."
She added: "We will work with the EU to eliminate this limited process as soon as possible after Brexit."
Meanwhile, Brexit Secretary Stephen Barclay sought to reassure MPs and businesses about the nature of checks on goods between Northern Ireland and GB proposed in the new Brexit deal.
He said it would be an "administrative process" which would involve "fairly straightforward data".
Mr Barclay clarified comments made by Boris Johnson on Wednesday when he said there would be no checks between Northern Ireland and GB.
"It is the case the prime minister was distinguishing between the paperwork that is required, which will be done digitally and is a single form, rather than actually introducing physical checks.
"In the coming months, we will need to work both within the United Kingdom and with the European Union to discuss how to eliminate the limited and administrative processes," Mr Barclay said.
DUP Westminster leader Nigel Dodds urged Mr Barclay to "take seriously" concerns raised by PSNI Chief Constable Simon Byrne, including warnings about the risk of loyalist violence.
He said: "You are really in danger here of causing real problems with the Belfast Agreement, with the St Andrew's Agreement, the political institutions and political stability in Northern Ireland by what you are doing to the unionist community.
"Please wake up and realise what is happening here. We need to get our heads together here and look at a way forward that can solve this problem. Don't plough ahead regardless, I urge you."
Secretary of State Julian Smith insisted yesterday that checks will be minimal after Brexit, but he was to give any further detail.
Mr Johnson has previously said fresh regulatory and customs checks in the Irish Sea would not happen on his watch.
Shadow Secretary of State Tony Lloyd said: "The government is in complete disarray about the impact of its sell-out Brexit deal on Northern Ireland.
"The Brexit Secretary says there will be border checks, the prime minister claims there won't be, and the Home Secretary cannot say for sure one way or the other.
"Boris Johnson should come to Parliament at the earliest opportunity to clarify the government's position and apologise for misleading MPs about the consequences of his Brexit deal on trade within the UK."
