Breakthrough: UK and EU reach post-Brexit trade agreement

Britain and the European Union have struck a provisional free-trade agreement that should avert New Year chaos for cross-border traders and bring a measure of certainty for businesses after years of Brexit turmoil.

With just over a week until the U.K.'s final split from the EU, the U.K. government said the "deal is done."

British Prime Minister Boris Johnson and European Commission President Ursula von der Leyen are expected to make statements imminently.

The deal should ensure the two sides can trade in goods without tariffs or quotas. But despite the breakthrough, key aspects of the future relationship between the 27-nation bloc and its former member remain uncertain.

The British and European parliaments both must hold votes on the agreement, though the latter may not happen until after the U.K. leaves the EU's economic embrace on Jan. 1.

Months of tense and often testy negotiations gradually whittled differences between the two sides down to three key issues: fair-competition rules, mechanisms for resolving future disputes and fishing rights. The rights of EU boats to trawl in British waters remained the last obstacle before it was resolved.

However, key aspects of the future relationship between the 27-nation bloc and its former member remain unresolved.

Johnson had insisted the U.K. would "prosper mightily" even if no deal were reached and the U.K. had to trade with the EU on World Trade Organization terms. But his government has acknowledged that a chaotic exit was likely to bring gridlock at Britain's ports, temporary shortages of some goods and price increases for staple foods.

The EU has long feared that Britain would undercut the bloc's social, environmental and state aid rules after Brexit,...