LONDON (AP) — The British government said Friday it will introduce a bill next week to override parts of the Brexit trade treaty it signed with the European Union before the U.K. quit the bloc in 2020. The move will be a major escalation in a festering U.K-EU dispute over trade rules for Northern Ireland.

British Prime Minister Boris Johnson’s spokesman, Jamie Davies, said “the bill has been agreed by the relevant cabinet committees and will be introduced to Parliament on Monday.”

The legislation, if approved by lawmakers, would scrap parts of a trade treaty with the EU that Johnson signed less than two years ago, by removing checks on goods entering Northern Ireland from the rest of the U.K.

The EU has threatened to retaliate, raising the specter of a trade war between the two major economic partners.

Some legal experts say the move is unlawful but the U.K. government says it will “publish a summary of the legal advice” it has received about the legislation.

Northern Ireland is the only part of the U.K. that shares a border with an EU country, Ireland. When Britain left the European Union and its borderless free-trade zone, the two sides agreed to keep the Irish land border free of customs posts and other checks because an open border is a key pillar of the peace process that ended decades of violence in Northern Ireland.

Instead, to protect the EU’s single market, there are checks on some goods, such as meat and eggs, entering Northern Ireland from the rest of the U.K.

British unionists in Northern Ireland say the new checks have put a burden on businesses and frayed the bonds between Northern Ireland and the rest of the U.K. — seen by some unionists as a threat to their British identity.

Britain’s Conservative government says the Brexit rules also are undermining peace in Northern Ireland, where they have caused a political crisis. Northern Ireland’s main unionist party is blocking the formation of a new power-sharing government in Belfast, saying it won’t take part until the Brexit trade rules are scrapped.

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