Petro Yezhor, police spokesman for the city of Rivne, said several unidentified assailants on Wednesday evening broke a memorial plaque and street lamps at a site commemorating the killing of 17,500 Jews during the Holocaust.
Yezhor said Thursday that the perpetrators used the metal parts from the broken street lamps to compose insulting phrases and lay them out on the site. Police in the city, around 350 kilometers (215 miles) west of the capital Kiev, are investigating.
The Jewish community leader in Rivne, Hennady Frayerman called the incident "horrific."
Some 1.4 million of Soviet Ukraine's 2.4 million Jews were executed, starved to death or died of disease during World War II.