Germany joined France on Tuesday in berating the US for negotiating a security pact in secret with Australia and Britain that cost Paris a lucrative defence deal, while the EU’s top official said such behaviour was unacceptable.

In a concrete signal of the bloc’s outrage, EU ambassadors postponed preparations for an inaugural trade and technology council on September 29 with the US, a gathering that was trumpeted as a major advance in the transatlantic alliance.

“One of our member states has been treated in a way that is not acceptable, so we need to know what happened and why,” European Commission president Ursula von der Leyen said in defence of France.

France said it was assessing all options in response to Australia’s scrapping of a $40 billion submarine contract last week, while its biggest EU ally, Germany, rallied behind it, saying Washington and Canberra had damaged trust between allies that would be difficult to rebuild.

German European affairs minister Michael Roth said the EU needed to overcome its differences and speak with one voice. “We all need to sit down at a table; lost trust has to be rebuilt,” he said.