Poland's parliament will be suspended at the close of business on Wednesday until after an election on October 13, its speaker said, prompting opposition lawmakers to accuse the right-wing government of secretly plotting to push through extra bills.

This parliamentary session had been due to end on Friday anyway. But by approving a motion merely to suspend, not terminate, the current session, the ruling nationalist Law and Justice Party (PiS) ensures that the outgoing parliament - in which it has a majority - reconvenes after the election for a short period before the new lawmakers can take their seats.

The opposition fears PiS, which they and the European Union accuse of undermining the rule of law, will use that small window after the election to push through additional bills. PiS, which is tipped to win the election, denies any such intention.

"We have a one-day session today, we announce a break and we continue (this session) on October 15 and 16. This is nothing extraordinary," said the speaker of the lower house, Elżbieta Witek, a PiS lawmaker.

Witek said PiS would not add new items to the parliamentary agenda on October 15 and 16 and that the earlier suspension would allow lawmakers to focus on election campaigning.

But the opposition said such a break was unprecedented in Polish parliamentary history.

"It means that PiS has some kind of a hidden plan - it either does not believe the election result will be positive for them and wants to play safe, or it wants to prepare some draft law, which could not have been adopted under normal conditions," Małgorzata Kidawa-Błońska from the main opposition group Civic Coalition told private radio TOK FM.

"You don't do such things out of love for the lawmakers. For sure it does not bode well," added Kidawa-Błońska, who is Civic Coalition's candidate for prime minister.

Other lawmakers suggested PiS might be hiding bad economic news from the voters and would amend its budget plan after the election, before the new parliament can be sworn in.

"Do they want to introduce some changes just after the election, about which they don't want to say a word ahead of the election because it may influence their result?" said Władysław Kosiniak-Kamysz, head of the Polish Peasant Party (PSL).