By Adam Easton
BBC News, Warsaw
Thousands of people in Warsaw have been rallying in rival protests - in support of the government and against it.
Supporters of the opposition have demanded early elections
Polish police said about 11,000 people took part in an opposition rally calling for early elections.
And two separate rallies in support of the government drew around 10,000, people they added.
The rallies come after a film was broadcast allegedly showing a prime minister's aide attempting to buy the support of a member of the opposition.
The film has thrown Prime Minister Jaroslaw Kaczynski's attempts to rebuild a stable parliamentary majority for his governing coalition into disarray.
But Mr Kaczynski has said the tape merely showed normal political bargaining.
Supporters of Poland's main opposition party, the centre-right Civic Platform, gathered in the historic centre of Warsaw to demand early elections.
Some held banners accusing the governing conservatives of lying in a direct reference to the secret film.
The affair was particularly embarrassing for the governing Law and Justice party because it has staked its reputation on being above political sleaze.
Meanwhile, across the city, Mr Kaczynski told a rally of his supporters that life in Poland is improving under his government.
He said he would continue his efforts to build a stable majority.
The opposition has filed a motion to dissolve parliament to trigger snap elections.
But without the support of the governing Law and Justice party it looks likely to fail.