Berlin: Italian President Giorgio Napolitano cancelled a dinner with the German opposition’s chancellor candidate on Wednesday after he described Italian former premier Silvio Berlusconi and comic-turned-politician Beppe Grillo as “clowns”.

Peer Steinbrueck, a Social Democrat who will take on Chancellor Angela Merkel in Germany’s next national election in September, has a reputation for gaffes and his remark created the first diplomatic incident of his accident-prone campaign.

Steinbrueck said on Tuesday he was “appalled that two clowns have won” Italy’s February 24-25 election. The vote was actually inconclusive with no party garnering a majority in parliament, although Grillo’s anti-establishment party surged dramatically.

Napolitano, an 87-year-old former communist with no natural affinity for Berlusconi or Grillo, now faces the difficult task of trying to appoint a coalition government.

Italian media said he had expressed concern about “populism” after the election result in a private meeting during his visit to Germany, but these comments could not be confirmed.

As head of state, he may have felt duty-bound to defend the dignity of Italy’s political institutions.

The German candidate’s spokesman said Napolitano cancelled “because of Steinbrueck’s remarks on Tuesday” and added that the SPD politician “understood Napolitano’s domestic political reasons for cancelling”.

Napolitano’s spokesman was unavailable for comment.

Napolitano and Steinbrueck had been scheduled to meet over dinner at a Berlin hotel. Napolitano, who visited Munich on Tuesday and Wednesday, was due to meet Merkel in the German capital on Thursday.

Steinbrueck made it absolutely clear in his comments to an SPD rally in Potsdam he was referring to Grillo and Berlusconi, calling the latter “clearly a clown with a testosterone boost”.

“My impression is that two populists won,” he said.

Berlusconi, a scandal-ridden billionaire media mogul, is very unpopular in Germany and slated often in the media.

But Steinbrueck did himself no favours with his frank talk.

German politicians are expected to strike a serious tone and refrain from interfering in the internal affairs of European partners. On Twitter, some commentators dismissed the acerbic Steinbrueck as the “real clown”.

“Steinbrueck behaves like a bull in a china shop,” said Michael Meister, deputy leader of Merkel’s conservatives in the Bundestag (lower house of parliament). He accused Steinbrueck of damaging Germany’s reputation abroad with such comments. Some SPD politicians also criticised Steinbrueck for his utterance.