Poland is launching a probe into the wiretapping of officials after recorded private conversations appear to reveal unsavoury deals, prosecutors say.
One recording of a conversation between the central bank chief and interior minister has stirred public outrage.
The two men allegedly discussed how the bank could help the government deal with a budget deficit and increase its chances of re-election in 2015.
Under Polish law, the central bank must remain independent of politics.
Transcripts of the recordings, which were made at a restaurant in Warsaw regularly frequented by the political elite, were published by Wprost magazine.
The magazine has not revealed how it obtained the recordings, which were made in July last year.
An investigation has been opened at the request of Interior Minister Bartlomiej Sienkiewicz, acting in the capacity of the victim, a spokeswoman for the Warsaw prosecutor, Renata Mazur, said.
In the recording, the head of the National Bank of Poland, Marek Belka, is allegedly heard requesting the finance minister, who was then Jacek Rostowski, be removed, in return for the bank's intervention in propping up the national economy in the event of an emergency.
Mr Rostowski was replaced four months later - but Prime Minister Donald Tusk has denied this was as a result of the talks and has spoken out in defence of both men.
Speaking on Monday, Mr Tusk described the leaked recordings as "an attempt at a coup d'etat, bringing down the Polish government by illegal means".
He said he had no plans to fire Mr Sienkiewicz despite coming under pressure from the main opposition Law and Justice party.
Opposition leader Jaroslaw Kaczynski has called for the government to step down over the leaks and says he will call for a vote of no confidence if Mr Tusk fails to do so.
Meanwhile, Polish President Bronislaw Komorowski has expressed concern about "the security of the Polish currency and the stability of the economy", in the wake of the revelations, Reuters news agency quotes his spokeswoman as saying.
It is illegal for anyone to bug or wiretap to gain unauthorised access to information in Poland, and sentencing for the crime can fetch up to two years in prison.