The United States is delaying a deal to remove Trump-era tariffs on UK steel and aluminum as Washington's concerns over post-Brexit trade rules affecting Northern Ireland rise, the Financial Times reported today.

In a communication seen by the newspaper, a US Commerce Department official was quoted as saying that talks with the UK on easing metals tariffs could not move ahead.

The official cited US concerns at British threats to trigger Article 16, the report said.

Article 16 of the protocol allows either side to unilaterally suspend elements of the deal if it creates serious economic, societal or environmental problems.

The administration of former President Donald Trump introduced 25% and 10% tariffs on steel and aluminum imports,citing national security concerns, prompting retaliatory measures from the European Union on goods such as motorcycles,whiskey and tobacco.

Britain incorporated those into its new independent tariff system when it completed its exit from the EU at the end of 2020, but is now reviewing the list of products to help protect UK-specific interests.