German central bank chief on Wednesday threatened to block plans to finance troubled eurozone partners through the International Monetary Fund (IMF), unless countries outside the eurozone are allowed to join the rescue operation.

Speaking in Frankfurt, President of the Bundesbank Jens Weidmann said, "If the conditions are not met, then we can not agree with this line of credit too."

His words came just days after EU leaders pledged at a summit meeting last week to pump 200 billion euros (267 billion U.S. dollars) into IMF coffers to help the eurozone, which is struggling to boost its own rescue fund to one trillion euros.

"If the U.S. and other major donors say they do not step up, then we also think that the public financing program will become problematic," Weidmann said.

He said that at the moment the Bundesbank was in principle willing to transfer up to 45 billion euros to the IMF. However, it must be ensured that the burden is shared fairly among the euro member countries.