The Bank of England has warned that the need for action is now “pressing” to ward off the risks to trillion of pounds of financial products from a no-deal Brexit.
Following its Financial Policy Committee meeting last week, the Bank said "timely action" is needed from the EU to protect against disruption to derivatives, insurance contracts and the transfer of personal data.
Without this, the measures needed to mitigate threats will be "disruptive and costly", it cautioned.
The FPC said: "There has been considerable progress in the UK to address these risks, but only limited progress in the EU.
"In the limited time remaining, it is not possible for companies on their own to mitigate fully the risks of disruption to cross-border financial services.
"The need for authorities to complete mitigating actions is now pressing."
The EU has not taken action
It marks the latest warning shot from the Bank after it said in June that the EU needed to do more to prevent Brexit causing havoc in markets.
The Bank estimates that £41 trillion of derivatives face legal uncertainty after Brexit on March 29 unless the EU takes action to ensure continuity of existing rules.
The UK is passing legislation through Parliament to allow EU-based providers of insurance policies and centrally cleared derivatives to continue to service their UK customers.
But the EU has yet to take similar action.
The FPC statement, following its October 3 meeting, also saw it confirm that the UK banking system is strong enough to withstand even a "disorderly, cliff-edge" Brexit without the need for UK lenders to bolster their balance sheets further.
The Bank also confirmed that the results of its annual health check for the UK's biggest lenders will be published on December 5.
The FPC raised concerns over a surge in leveraged lending, including to UK businesses in the report, and is reviewing potential risks to UK financial stability "more intensively".
It said the global leveraged loan market was now larger than - and growing as quickly as - the US subprime mortgage market was in 2006, which led to the credit crunch and subsequent financial crisis.
The Bank added that, while mounting trade tensions between the US and China do not pose a direct risk to UK financial stability, they could trigger a "more severe tightening of global financial conditions".