The Ukrainian and Polish presidents have marked the anniversary of World War II massacres of Poles by Ukrainian nationalists that have been a source of tension between the allies.

Warsaw has positioned itself as one of Kyiv’s staunchest supporters since Russia’s invasion in 2022.

However, the Volhynia massacre, in which historians say tens of thousands of Poles perished, has continued to hang over the ties.

It has also become more prominent ahead of the July 11 anniversary of one of the bloodiest days of a series of killings that took place from 1943 to 1945.

Television footage showed Ukraine’s Volodymyr Zelenskyy and his Polish counterpart Andrzej Duda in a church in the western Ukrainian city of Lutsk on Sunday during a service held in memory of the victims.

“Together we pay tribute to all the innocent victims of Volhynia! Memory unites us!,” Mr Duda’s office wrote on Twitter.

The service was attended by the heads of the largest Orthodox and Catholic churches in Ukraine and the head of the Polish Bishop’s Conference, Archbishop Stanisław Gądecki.

The Ukrainian president’s chief of staff, Andriy Yermak, wrote on Telegram that Ukraine and Poland were “united against a common enemy who dreamed of dividing us”.

The head of Mr Duda’s office said the fact that the presidents were commemorating the victims together was “historic”, but that more work was needed.

“This is not the end of this difficult road, explaining to our Ukrainian friends about the historical truth, it will of course be continued,” Paweł Szrot told private broadcaster, Polsat News.

In a post on Twitter, Mr Zelenskyy said he had a “brief but very substantive” discussion at the event with Mr Duda about the upcoming NATO summit in Vilnius, where Ukraine is hoping for decisions that will hasten its goal of membership in the alliance.

“We agreed to work together to get the best possible result for Ukraine,” Mr Zelenskyy wrote.

The massacre caused an unusually public row between Poland and Ukraine earlier this year, after a Polish foreign ministry spokesman said that Mr Zelenskyy should apologise and ask for forgiveness for the events in Volhynia.

However, Ukraine’s parliament speaker Ruslan Stefanchuk moved to defuse tensions in May when he told the Polish parliament that Kyiv understood Poland’s pain.

On Friday, Polish Prime Minister Mateusz Morawiecki visited western Ukraine to pay tribute to the victims.

The killings were carried out between 1943 and 1945 by the Ukrainian Insurgent Army and the Organisation of Ukrainian Nationalists under the leadership of Stepan Bandera.

Polish historians say that up to 12,000 Ukrainians were also killed in Polish retaliatory operations.

The Polish parliament has said that the murders bore elements of genocide.

Ukraine has not accepted that assertion and often refers to the Volhynia events as part of a conflict between Poland and Ukraine which affected both nations.

Reuters