The German government wants to resist or delay increasing the size of the eurozone’s financial “firewall” against contagion from the Greek debt crisis, in the face of mounting pressure from its partners, the International Monetary Fund and the US administration.

Steffen Seibert, spokesman for Angela Merkel, the German chancellor, insisted yesterday that Berlin saw no need to increase the size of the permanent €500bn European Stability Mechanism. “The German government’s position has not changed,” he said. “That means no, it is not necessary.”

Ms Merkel and her finance minister, Wolfgang Sch?uble, are looking isolated in the face of strong pressure from Christine Lagarde, managing director of the IMF, and the other 16 members of the European monetary union. Mr Sch?uble is likely to face further pressure on the subject this weekend at a meeting of G20 finance ministers in Mexico City.