EU's #Juncker says fun is over as he heads to meet Azerbaijan's Aliyev

"Thank you, have a nice day," Juncker told reporters at the end of a news conference. "I will now see the president of Azerbaijan, so the nice part of the day is over."

Azeri President Ilham Aliyev was in Brussels to discuss new pipelines that would carry Azeri gas to Europe. Baku is keen to tap into the bloc's market of 500 million people and the EU is equally eager to reduce its dependence on Russian gas.

But at home, Aliyev - in office since 2003 - is accused of centralizing too much power in his own hands, heavily restricting free speech and cracking down on independent media.

Azeri officials were not immediately available to comment on Juncker's remark. But his spokeswoman said the two discussed energy and economic cooperation, and that Juncker highlighted the need for respecting human rights and fundamental freedoms.

Juncker, a former prime minister of Luxembourg who has headed the EU's executive Commission since 2014, is known for his quips and flouting of diplomatic protocol.

Last Friday, replying to a journalist's question as to what posed the biggest threat to the EU, the veteran Brussels insider joked: "Me."

Juncker once greeted Hungarian Prime Minister Viktor Orban, who is accused by critics of stifling dissent at home, by saying: "Hello dictator!"

Donald Tusk, the head of the European Council that represents the 28 member states of the EU, stuck to more diplomatic language during his joint news conference with the Azeri president earlier on Monday.