Germany insisted Wednesday that there was no necessity to boost the volume of the European Stability Mechanism (ESM), a crucial crisis firewall taking effect in July.

"The stance of the federal government has not changed," German government spokesman Steffen Seibert told reporters.

There is no need to expand the size of the ESM, a permanent rescue funding program to succeed the temporary European Financial Stability Facility (EFSF), especially after clouds over Italian and Spanish bond markets became thinner recently, said Seibert.

The comment came one week ahead of a closely watched eurozone summit, which focuses on reviewing the lending capacity of the ESM and paving the way for its entering service. Many eurozone countries and the International Monetary Fund have been calling on leaders to agree on expanding the ESM during the meeting, a topic that Germany showed little interests.

Since tensions on bond markets of major eurozone economies eased, Germany gave its priority to making decisions on "in what form and in how many tranches we pay in capital to the ESM," Seibert said.

He added that Germany was ready to send a "strong signal" in this respect.

Berlin had said that it was considering paying its contribution of 80 billion euros to the ESM at one fling, rather than through five annual payments as initially planned.