"Let us be clear: We will not prune the eurozone to a more selective club," he said in Florence, Italy, The Daily Telegraph reported Saturday.
"That would be contrary to the letter and the spirit of the European political pact, as embodied in the treaties," he said.
His remarks came after British Prime Minister David Cameron questioned how long the eurozone countries could hold together and amidst reports that German Chancellor Angela Merkel would support proposals to allow eurozone countries to exit the international partnership.
France and Germany have reportedly discussed the idea of cutting fiscally beleaguered Italy and Greece out of the eurozone.
"These are very worrying times. It's a very difficult time for the eurozone, there's real turbulence in the markets, real question marks over whether countries can deal with their debts and a big question mark over the future of the eurozone," Cameron said in a radio address Friday.
The remarks were followed by a warning from Rompuy.
"If the eurozone's integrity would not be preserved, one should not take the continued functioning of the internal market for granted," he said.
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