(AFP) European Commission chief Jean-Claude Juncker berated euro MPs who heckled him for looking at his phone during a parliamentary debate Tuesday, saying he was texting the Greek prime minister.

Juncker's exchange of messages with Alexis Tsipras came just hours before an emergency eurozone summit called after debt-stricken Greeks overwhelmingly voted 'No' to further austerity measures in a referendum at the weekend.

"Stop all this chatter about me looking at my telephone all the time. I am texting, as they say in Franglais, with the Greek prime minister," a clearly irritated Juncker, speaking in French, told the European Parliament in Strasbourg.

"I don't know if you will have the chance to do the same but I have to do that today. I am doing my work, so stop this stupid banter, for which there is no cause."

Former Luxembourg premier Juncker was heckled by several MEPs, including members of the eurosceptic UK Independence Party who had placed Union Jack flags on their desks, over his handling of the Greek crisis.

For months Juncker was the link man with leftist premier Tsipras, but after a series of late-night meetings and chummy photo opportunities produced no bailout deal, Juncker said last week he felt "betrayed" by the calling of the referendum.

On Tuesday he again accused the Greeks of a "serious error" in walking out of talks but said that his "wish is that a 'Grexit' should be avoided."

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