Italian Prime Minister Silvio Berlusconi appeared to be playing "hide and seek" before greeting his guest - German Chancellor Angela Merkel.
Mr Berlusconi, 72, who is famous for his practical jokes, hid behind a large column ahead of their talks in Trieste as Mrs Merkel's entourage walked past.
He called out "coo coo", prompting Mrs Merkel to turn around, saying "Oh, Silvio", reporters on the scene said.
The two are seen laughing and embracing warmly, before starting the talks.
The German and Italian leaders were discussing the global economic crisis.
Mr Berlusconi's previous practical jokes at formal gatherings include making the Italian horned 'cuckold' gesture behind a Spanish minister during a group photo of EU leaders in 2002.
He is also prone to more ill-judged jokes, such as confessing to using "playboy tactics" in 2005 to enlist the support of Finnish President Tarja Halonen for Italy to host the European Food Safety Authority.
More recently, Mr Berlusconi faced criticism for calling US President-elect Barack Obama "handsome, young and suntanned" during a visit to Moscow.
Carla Bruni, the Italian-born wife of President Sarkozy of France, said that the remark made her "happy to be no longer an Italian citizen".
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