Poland's prime minister says a new law that gives the justice minister power over prosecutors is intended to restore people's trust in the justice system, but critics say it has political motives.

The law that takes affect Friday was introduced by the new conservative Law and Justice government, which is making sweeping changes to state offices and businesses. It gives the justice minister influence over every investigation because it joins his office with that of the chief prosecutor; a return to a pre-2010 system.

The opposition says the move unfairly gives the government political power over vital investigations and says Justice Minister Zbigniew Ziobro has a reputation for being politically motivated.

Prime Minister Beata Szydlo said Thursday the move should help prosecute "those who violate the law and are dishonest."