Speaking the same day Theresa May announced Boris Johnson as the UK's new foreign secretary, Schulz delivered some harsh words for the new prime minister and her government, saying they must break the country's "dangerous vicious circle" before it also impacts the EU.

While saying that the EU would "work constructively" with the new government, Schulz also criticized May for what he perceived as her willingness to put party politics ahead of her country.

"The composition of the new cabinet [under May] shows that it has less to do with the future of the country than it does with the ensuring the cohesion within the Tory party," Schulz said in an interview with German newspaper "Süddeutsche Zeitung," to be published on Friday.

Europe reacts to May's choices

His comments come as other European politicians reacted critically to the news of Johnson's posting. Among those most vocal about their dissatisfaction with the choice was German Foreign Minister Frank-Walter Steinmeier, who called the ex-mayor of London "irresponsible."

"People [in the UK] are experiencing a rude awakening after irresponsible politicians first lured the country into a Brexit and then, once the decision was made, bolted and didn't take responsibility," he said during an address at Greifswald University.

The French foreign minister was also not so pleased with Johnson, even if he wasn't as harsh as his German counterpart. The decision to make Johnson foreign minister was a "sign of the political crisis" in the UK following the Brexit vote, Jean-Marc Ayrault said in a radio interview. Nonetheless, he said he "overall wasn't worried" about Johnson.

"But you already know his style and method," Ayrault added. During the campaign leading up to the Brexit vote, Johnson "had lied a lot."

blc/bw (AFP, dpa)