The notion that Sunday's referendum would persuade Germany to spend more taxpayers' money on bailing out Greece was angrily dismissed by numerous renegade Christian Democrat (CDU) MPs in media interviews. "We must now end this experiment with the reform-reluctant Greeks," said Christian von Stetten, head of the CDU's small business association group in parliament. Earlier, he described Greek government representatives as "rip-off merchants" and "conmen".

Andreas Scheuer, general secretary of the Bavarian wing of Ms Merkel's conservatives, was more emphatic. "Greece has said No and as far as we are concerned that means no to negotiations and to a further aid package," he told Germany's 'Bild' newspaper.

Other leading conservatives said they agreed with the finance minister Wolfgang Schäuble, who has said that the "honest and consequent approach" would be for Greece to leave the eurozone.

Ms Merkel has been at odds with her finance minister by insisting over past months that Greece should remain inside.