BRUSSELS (Reuters) - Euro zone finance ministers will meet on Tuesday to prepare an emergency euro zone summit on Greece later in the day, a spokesman for Eurogroup President Jeroen Dijsselbloem said on Sunday. "Additional Eurogroup on Tuesday July 7 to prepare euro summit on Greece, starting time to be confirmed," Michel Reijns said on Twitter. European Council President Donald Tusk earlier called a euro zone summit for 6 p.m. (1700 BST) on Tuesday after Greeks voted overwhelmingly to reject the terms of a bailout. (Reporting by Adrian Croft; Editing by Alastair Macdonald)