The EU's chief negotiator with the UK, Michel Barnier, emphasised Wednesday that Britain must accept standards on a par with the bloc's if it wants a post-Brexit deal to kick in from next year.
Barnier was underlining the EU's core position ahead of EU-UK talks on a future relationship that are to begin on Monday in Brussels and alternate between that city and London for the rest of this year.
It is also the biggest point of contention.
The British government insists that the whole point of Brexit was to free itself of EU rules, and it has declared that it will eschew European norms for its own set of standards.
That strategy would come with a cost, namely in increased trade friction through possible tariffs, Barnier warned.
Even if a free trade deal with Britain were struck, he added, checks on British goods were inevitable.
"We cannot take the risk that the UK becomes a kind of assembly hub for goods from all over the world, allowing them to enter the single market as 'British goods'," he said.
Barnier also said that "nobody contests" Britain's right to set its own rules.
Agreeing on common standards on the environment, labour, taxation and state subsidies was "a question of pragmatism", he said, not "sovereignty".
Barnier also shot down Britain's stated desire of replicating the trade deal Canada has struck with the EU, stating bluntly: "The UK says it wants Canada but the problem with that is that the UK is not Canada."
EU-British trade was ten times greater and Britain was far closer, making it "a direct competitor that is right on our doorstep", he said.
When it comes to EU trade deals, he explained, "we need to tailor them to the reality of our relationships".
- EU won't be a 'risk taker' -
He also objected to Britain's financial hub having a general carte blanche to operate across the EU's single market, offering instead sector-by-sector access that could be quickly cut off.
"The UK may not want to be a rule taker, okay. But we do not want to be the risk taker for the next financial crisis," Barnier said.
While predicting that Britain was not seeking to become a deregulated "Singapore-on-Thames", Barnier raised a concern that recent British government declarations suggested the UK was "moving back" from commitments made under the Brexit withdrawal agreement.
That treaty, struck late last year, permitted Britain to ease out of the the EU following its departure at the end of January. For the rest of this year, the country effectively gets to continue trading like an EU member while the future relationship negotiations take place.
But British Prime Minister Boris Johnson's ministers and spokesman have been questioning the agreement's requirement to check goods going from Britain to the UK's territory Northern Ireland, which remains largely under EU rules.