The ECB in Frankfurt could not be immediately reached for comment on the advance excerpts of articles to appear on Tuesday in the two German newspapers, die Welt and Sueddeutsche Zeitung.

Asked about the reports, Olli Rehn, the EU Economic and Monetary Affairs commissioner, told journalists in Brussels the EU was working closely together with the ECB and IMF.

"I do not have any clue what you're talking about and we work very constructively with (ECB) President (Mario) Draghi and the other troika partners," Rehn said.

The conservative Die Welt and liberal Sueddeutsche Zeitung said some ECB members were concerned that participation in euro zone rescue efforts could create a conflict of interest for the ECB and compromise its independence.

"The level of discomfort has reached such a level that there are considerations among some important members of the ECB to leave the troika entirely," Die Welt reported, citing a financial source it did not identify.

It quoted a government source in Berlin as saying there were two reasons for the concerns. It had become quite normal for the ECB to take part in rescue efforts for struggling euro zone countries.

Secondly, Die Welt said, the ECB's political influence was growing. Together with the IMF and the EU, it was imposing gigantic adjustment and reform programmes on ECB nations.

Die Welt said not everyone in the ECB had the same concerns.

The Sueddeutsche Zeitung quoted one ECB source as saying: "The problem is there. But we only have an advisory role in the troika and not a deciding role. The programmes are signed by the Commission and the IMF."