Poland's centre-right government has found its future called into question after leaked audio recordings suggested it cut a deal with the central bank to boost the budget and garner political support.

The fallout led Prime Minister Donald Tusk to raise the spectre of snap elections as polls show plummeting support for his party Civic Platform (PO) and increased backing for the opposition Law and Justice (PiS.

Footage of government agents manhandling journalists from the Wprost weekly magazine that leaked the secret audio recordings has also raised alarm at home and abroad over press freedom.

The scandal "will fundamentally influence Polish politics and the opposition will attempt to extract maximum benefit," leading Warsaw analyst Edmund Wnuk-Lipinski told AFP.

The crisis erupted Sunday with the release of the secret recordings, which were allegedly taken in a Warsaw restaurant in July 2013.

They purportedly feature central bank chief Marek Belka telling Interior Minister Bartlomiej Sienkiewicz he would support the government's economic policy if then finance minister Jacek Rostowski resigned.

Tusk has denied sending his minister to meet Belka, who in the recording says Rostowski's "decommission" would be "essential" for the central bank to support government policy.

Rostowski was fired in November after six years on the job but the bank denied any deal was struck, saying Belka's comments were taken out of context.

Analysts have dubbed the ensuing political fallout as the country's worst since the two-term Tusk took office seven years ago. The next regularly scheduled elections are due next year.

- Press freedom -

Images of government agents attempting to wrestle a laptop out of the arms of Wprost's editor-in-chief have sparked international ire.

"It's the first time since 1989 (end of communism) that this has happened and all journalists are against you Mr. Prime Minister," top Polish journalist Monika Olejnik said at a press conference.

The Vienna-based OSCE rights watchdog slammed the raid, saying it was "conducted without a previous court decision".

"These kinds of investigation methods are unacceptable as they have a chilling effect on investigative journalism and could stifle media freedom," OSCE media representative Dunja Mijatovic said in a statement Thursday.

The famously unflappable Tusk has so far resisted calls for him to quit by PiS leader Jaroslaw Kaczynski.

According to Warsaw political analyst Eryk Mistewicz, the leaks are a "velvety coup d'etat. Political blackmail aimed at ousting the prime minister".

Opinion polls this week showed the PO down to 25 percent public support, with PiS climbing to 32 percent.

Rising voter dissatisfaction with Tusk became clear last month when PO won the European Union parliament elections by less than a percentage point ahead of PiS.

- Critical juncture -

The scandal comes as the ex-communist state -- and current NATO and EU member -- grapples with security concerns sparked by the escalating crisis in neighbouring Ukraine.

Tusk has accused those behind the recordings of seeking to weaken Poland at this critical juncture by trying to topple his administration.

"Above all, we must find out who made the recordings and why," Adam Szejnfeld, a close Tusk aide, said Friday.

He suspects that either Polish or foreign intelligence agents taped the talks for financial or political gain.

"The last time that social pressure on politicians and the state was so strong was in the 1990s," Mistewicz said, adding that he doubts the scandal would result in a snap election.

But that could change. Polish media reports indicate there are several hundred hours of recordings of politicians and top businessmen that could still surface.