The British Prime Minister is reportedly drawing up new legislation that will override the Brexit withdrawal agreement on Northern Ireland.
The Financial Times claims that it would affect areas including state aid and Northern Ireland customs.
The move could risk the collapse of talks with the EU over a free trade deal.
The British Labour Party says it would be an act of 'immense bad faith'.
The EU's chief Brexit negotiator has accused the UK of 'wanting the best of both worlds' in the Brexit negotiations.
Speaking to France Inter radio, Michel Barnier has warned the current impasse is "very serious" and has urged Britain to come to a fair agreement as talks resume this week.
The Minister for Foreign Affairs Simon Coveney says it's "a very unwise way to proceed".
— Simon Coveney (@simoncoveney) September 6, 2020