BERLIN (Reuters) - The leader of Poland's ruling eurosceptic Law and Justice (PiS) party on Thursday rejected a European Union disciplinary procedure that is pressuring the government, and said the European Commission was overstepping its bounds.

The commission on Wednesday gave Poland three months to boost the powers of its constitutional tribunal, the next step in a procedure that could lead to the suspension of Warsaw's EU voting rights and the freezing of its EU funds.

"This process is wholly outside the EU treaty," PiS leader Jaroslaw Kaczynski told Germany's Bild newspaper in an interview. "It is nothing but a happy endeavor for the amusement of the EU commission and its bureaucrats."

Since winning elections last October, the party has imposed changes on the tribunal and Poland's public broadcaster that Brussels fears are undermining the EU's democratic standards.

Poland's 1997 constitution gives the tribunal power to block laws approved by parliament and the president, but the PiS-controlled parliament approved laws in December that require a two-thirds majority, not a simple majority, to pass verdicts.

Last week, after EU pressure, the Polish parliament voted to remove that requirement but introduced a clause allowing judges to postpone a ruling by six months if four judges agreed.

Kaczynski said Poland remained in discussions with the European Commission, but noted that other countries such as the Netherlands did not even have a constitutional court.

"Poland is a sovereign state. We want the same rights as all other EU countries. Not more, but also not less," the newspaper quoted him as saying.

PiS, backed by about 40 percent of Poles, has also sought to increase or solidify state control over economic sectors including banking, energy and chemicals.

Kaczynski said Poland remained a committed EU member and said he did not expect a referendum like the June 23 vote by Britain to leave the bloc.

"Ninety percent of the citizens would oppose an exit. We Poles are and remain convinced Europeans," he said.

Kaczynski said the EU should move away from its current centralized approach. "Brexit showed us where the problems lie. If we don't solve them we will not prevent but strengthen anti-EU movements in many EU countries."

He said he hoped Britain reversed course and stayed in the bloc.

Kaczynski also rejected concerns that Poland planned arrests and lawsuits against opponents after the pope concludes his visit to Poland. "There's nothing to these rumors. No one is arrest or persecuted for political reasons."

(Reporting by Andrea Shalal; Editing by Leslie Adler)