Jan Cienski in Warsaw -

Poland's government is plunging into yet another crisis as the ruling twin Kaczynski brothers jettison former allies and ministers in their increasingly chaotic attempt to purge the country of communist and post-communist influences.

The Kaczynskis have unleashed enormous political turbulence since coming to power in late 2005, but the latest scuffles show that dissension has now penetrated to the heart of their ruling Law and Justice party.

Suspicious minds

Ludwik Dorn, the twins' closest ally who was once known as the "third twin," sent an extraordinary letter to the Polish Press Agency earlier this week denouncing criticism he had been subjected to since resigning as interior minister last week and asking Jaroslaw Kaczynski, the prime minister, to give him temporary leave from his post of deputy prime minister.

"A situation has arisen, which from a moral and political perspective, is impossible for me to accept," Dorn wrote in his emotional letter.

He was reacting to criticism from the new interior minister, Janusz Kaczmarek, who had suggested in a series of interviews that Dorn had been unable to fully control his ministry and had not made much progress in unravelling the web of corruption the Kaczynskis claim envelops Poland.

Strangers in the house

The Kaczynski's swept to power on a promise to clean up the country, which they said was in the thrall of communist-era secret agents allied with criminals, shady business people and bent politicians. However, in more than a year in power, there have been no spectacular arrests and no proof that the key idea of the Kaczynskis is more than the stuff of conspiracy theories.

Dismissing Dorn "is a sign that Jaroslaw Kaczynski has decided to speed up the process of changes," reckons Jacek Kucharczyk of the Institute of Public Affairs, a think-tank.

The hunt for enemies, preferably ex-communists, is also behind last week's surprising departure of Radoslaw Sikorski, the defence minister.

Sikorski was removed after unsuccessfully trying to sideline Antoni Macierewicz, his former deputy and currently Poland's counter-intelligence chief. Macierewicz, who shares the Kaczynskis' conspiratorial world view, has been tasked with eliminating the military intelligence agency (WSI) and preparing a report on the agency's past wrongdoings. Even critics of the Kaczynskis concede that the WSI was never properly cleansed after the fall of communism in 1989 and was involved in many dubious intelligence and business deals.

Macierewicz is supposed to present the report on Friday, but the expectation is that it will provide little evidence to back up the Kaczynskis' thesis that post-1989 Poland has been so deeply corrupted by spies and agents that the country must be rebuilt from the ground up.

There is also disappointment that the new Central Anti-Corruption Bureau, the creation of which was one of Law and Justice's main aims in government, has failed to unearth any spectacular scandals.

Friction between the new elite law enforcement agency, which is under the prime minister's control, and the police and other departments under Dorn's authority were also one of the reasons for his dismissal.

Jaroslaw Kaczynski and his brother Lech, the president, are increasingly isolated. They have rooted out most of their party's independent barons – before Sikorski and Dorn, Kazimierz Marcinkiewicz, the former prime minister, was sent into exile, as was Stefan Meller, the foreign minister. The ministerial replacements tend to be less colourful, younger and completely slavish to the Kaczynskis.

"They have chosen people who are very loyal, that is the main criterion," says Jadwiga Staniszkis, a political scientist at the University of Warsaw.

While the current crisis creates problems for Jaroslaw Kaczynski, it does not spell the end of his government. That will only happen if the sex-for-jobs scandal currently swirling around his rural populist partners from the Self-Defence party makes it impossible to continue the coalition government

Send comments to Jan Cienski