He said Romaszewska told him: "Mr. President, I lived in a state where the prosecutors general had an unbelievably powerful position and could practically do everything. I would not like to go back to such a state."

A third bill, which Mr Duda did not veto, will allow the PiS to appoint its own judges in the Common Court.

Supporters of the bills say they would bring about necessary changes to a judicial system that many Poles feel is corrupt and inefficient.

The decision was praised as "difficult and courageous" by Lech Walesa, the former president and an icon of Polish democracy.

Mr Walesa had given opponents of the reforms a significant boost by joining them at a protest in Gdansk, his home city, last week.

It came after the EU threatened legal action against Poland over the reforms as it warned that they risked undermining legal independence.

Donald Tusk, the president of the European Council, said last week that there would be a "bleak outcome" if Poland pushed ahead with the reforms, while the European Commission threatened to strip the country of its voting rights.