Solidary Poland, a junior ally in the coalition led by Zbigniew Ziobro, the justice minister, has clashed with PiS over Europe, prompting speculation the government might collapse.

"Either (coalitionist - PAP) Solidary Poland and the remaining coalition partners accept our conditions so that we can be like one fist again, or we'll have an early election in the summer," the source said.

PiS and Solidary Poland are in a dispute over Ziobro's reluctance to close down a disciplinary chamber for judges at the Polish Supreme Court. The chamber's closure had been demanded by a European court and the European Commission, which says its existence impairs the independence of judges and hence violates EU laws.

The government has said it is willing to close down the chamber in its current form, and two bills proposing its liquidation - one authored by the Polish president, the other by PiS - are currently in the Sejm (lower house).

But Ziobro, who is also Poland's chief prosecutor, has rejected any moves to close the chamber, arguing that the European Commission is not empowered to question Poland's justice reforms.

The European Commission has blocked billions of euros in post-pandemic aid for Poland until the chamber is shut down.