Bannon, these people said, signalled to Germany's ambassador to Washington that he viewed the EU as a flawed construct and favoured conducting relations with Europe on a bilateral basis.

Three people who were briefed on the meeting spoke to Reuters on condition of anonymity due to the sensitivity of the matter. The German government and the ambassador, Peter Wittig, declined to comment, citing the confidentiality of the talks.

A White House official who checked with Bannon in response to a Reuters query confirmed the meeting had taken place but said the account provided to Reuters was inaccurate. "They only spoke for about three minutes and it was just a quick hello," the official said.

The sources described a longer meeting in which Bannon took the time to spell out his world view. They said his message was similar to the one he delivered to a Vatican conference back in 2014 when he was running the right-wing website Breitbart News.