"We should not fear ourselves and our history, but we should treat it and the friendship between our countries with respect. That is why we agreed to help our historians' work together and find a factual proof of what really happened," Klimkin said.
The Volhynia massacre was part of an ethnic cleansing operation carried out in Nazi-occupied Poland by the Ukrainian Insurgent Army (UPA) in 1943-1944. According to various estimates, up to 60,000 Polish citizens were killed in the conflict.
On Thursday, the Ukrainian parliament condemned Polish lawmakers' decision to recognize the Volhynia killings as genocide.