WARSAW, Poland — A Polish law that criminalizes accusing the Polish nation of crimes that were committed by Nazi Germany has taken effect.

The law has sparked a crisis with Israel, where officials fear its true aim is to repress research on Poles who killed Jews during World War II, something Polish officials deny.

As the law took effect Thursday, Polish and Israel representatives were in Jerusalem holding a first working meeting toward resolving a standoff over the law.

Poland’s president signed the law last month but also sent it to the constitutional court for review. Polish officials have said no criminal charges will be brought until the court has made its ruling, expected in several weeks.

But prosecutors are also already looking for cases in which Poland is defamed over its wartime activities.