European Council president Donald Tusk has hit out over "increasing threats" from the UK over the willingness to quit the EU without agreeing new trade terms.
Prime Minister Theresa May has repeatedly stated that "no deal is better than a bad deal" in order to stress her willingness to walk away from Brexit talks.
But speaking in the European Parliament, Tusk said: "The claims increasingly taking the form of threats that no agreement will be good for the UK and bad for the EU needs to be addressed."
He added: "A no-deal scenario would be bad for everyone, but above all for the UK because it would leave a number of issues unresolved. We will not be intimidated by threats and I can assure you they simply will not work."
Tusk's comments come after London mayor Sadiq Khan and Brexit secretary David Davis have both warned that failure to secure trading terms with the EU would have a negative impact on European member states.
May is expected to trigger Article 50 to launch the process in the final week of March.