Boris Johnson will act unilaterally to give supermarkets and their suppliers more time to adapt to post-Brexit trade arrangements in Northern Ireland in a major escalation of tensions with Brussels. The Prime Minister told the Commons: "The position of Northern Ireland within the UK internal market is rock solid and guaranteed... We leave nothing off the table in order to ensure we get this right." Brandon Lewis, the Northern Ireland Secretary, confirmed that the UK is extending the grace period for supermarkets agreed with the EU last year by five months. The move sparked a fresh row with the EU, which is jointly responsible for the Northern Ireland Protocol governing trade and new border checks in the province. The European Commission said the EU had "strong concerns" over the unilateral move because "this amounts to a violation of the relevant substantive provisions of the Protocol on Ireland/Northern Ireland and the good faith obligation under the Withdrawal Agreement." "This is the second time that the UK government is set to breach international law," said Lord Frost's opposite number Maros Sefcovic, referring to earlier UK threats to override the Withdrawal Agreement. The commission threatened retaliation through enforcement measures in the Withdrawal Agreement and trade deal in response. The temporary relaxation for checks on supermarkets and their suppliers had been due to expire at the end of this month under the terms of Northern Ireland Protocol, which is part of the Withdrawal Agreement reached in 2019 and which came into force this year. However, in a written ministerial statement published on Wednesday, Mr Lewis said suppliers moving goods between Great Britain and Northern Ireland will now not be required to fill out the extra paperwork for agrifoods when the deadline expires. Instead, the UK will unilaterally extend the deadline until October while continuing to try to secure agreement with the European Commission for a longer extension as requested by Michael Gove.