According to the agency, a motto glorifying Ukrainian nationalists and a flag were painted on the monument.
According to the city administration, workers were sent to eliminate the act of vandalism.
Sekerka himself stated that responsibility for this incident does not necessarily lie with Ukrainian nationalists or their supporters.
Earlier, Poland’s Deputy Prime Minister and Defense Minister Wladyslaw Kosiniak-Kamysh said Warsaw will block all attempts by Ukraine to join the European Union until the dispute between the two countries over the Volyn tragedy is resolved.