The British newspaper reported that Portugal, Croatia, the Czech Republic, Greece, Italy, Romania, and Slovakia submitted formal opinions and observations to Brussels, arguing that the British proposal could violate the post-Brexit agreement known as the 'Depthsor Framework'.

Portuguese sources cited by The Times claimed that the British bill "clearly contradicts the principles of the treaties, as well as the Windsor Framework Agreement," the legal mechanism agreed between London and Brussels in 2023 to ease customs controls between the EU and Northern Ireland.

The countries fear that the restrictions will create unjustified barriers to the free movement of goods across the borders between the United Kingdom and the European single market.

The newspaper said the issue could lead to formal talks between Brussels and London, and ultimately, to a legal dispute.

The measure to progressively raise the legal age for purchasing tobacco until a total ban was initially proposed by Rishi Sunak's Conservative government in 2023 and taken up again by the current Labour government of Keir Starmer.

Already approved by the House of Commons, the bill is expected to be debated this week in the House of Lords, the upper house of the British Parliament.

The British Ministry of Health assured The Times that the legislation is "fully compliant with international obligations within the framework of Northern Ireland".