Tensions between the UK and the EU over border checks on goods to Northern Ireland could end up in front of the European Court of Justice after the government stuck to its guns.
Brussels has accused the government of acting illegally after refusing to bring in full checks, as agreed in the 2019 post-Brexit deal.
The EU has brought seven lawsuits accusing the UK of failing to comply with the Northern Ireland protocol - but in responses today the government refused to budge.
The UK said it would continue a controversial grace period, it is understood, leaving the European authority contemplating further legal action.
Full checks on farm produce and other goods entering from Great Britain will continue to be suspended - an action Europe says is illegal and unjustified.
The government has said that the protocol over trade rules - designed to prevent a hard border between Northern Ireland and its southern neighbour, which remains in the EU - should be renegotiated.
No 10 yesterday (THURS) declined to comment on the situation, but sources say Whitehall plans to continue with its controversial grace period.
The Prime Minister's official spokesman said that Downing Street had "no comment" to make on the matter.
An EU spokesman said: "We will now analyse the reply before deciding upon next steps."
There has been speculation that PM Liz Truss will discuss the matter with her Irish counterpart Micheal Martin on the margins of the Queen's funeral.
The government is understood to hope that delaying checks will give space for permanent solutions to the dispute being found.
Northern Ireland has remained in the EU's single market, meaning imports from the UK are subject to customs declarations and often require checks on arrival.
The EU has been further angered by the UK's threat to override parts of the protocol with new legislation - which the bloc argues would break international law.
Britain also requested a meeting next week of the specialised Committee on EU Programmes amid a row over the UK's association with the Horizon scientific research initiative.
European Commission president Ursula von der Leyen will be in Westminster for the Queen's funeral on Monday.
It is unclear if she will be meeting Prime Minister Liz Truss while in London, although Ms Truss is expected to hold some talks with political leaders during their visits.
Neither side was planning to publish the document.
