VATICAN CITY (BLOOMBERG) - Pope Francis's stance on Russia's invasion has drawn sharp criticism from Ukraine's Catholics and prompted fears that angry believers may disrupt Holy Week rites.

The Vatican's decision to put a Ukrainian and a Russian side by side during a Good Friday celebration is being criticised for equating victims to their aggressors.

Ukraine's top Catholic cleric called the move "untimely" and "ambiguous".

An internal Vatican briefing described to Bloomberg said that Ukrainians working within the Vatican were disconcerted by the plan.

It also mentioned possible protests during the Stations of the Cross celebration at the Coliseum on Friday (April 15) in Rome, which Pope Francis is due to lead.

The Catholic leader has condemned the "senseless massacre" by Russian troops in Ukraine and the murder of civilians, women and children in Bucha, but he has never explicitly mentioned Russia as responsible for the war.

His appeals to end violence in the country have stopped short of directly calling on Russian President Vladimir Putin to stop the invasion.

"Sitting in warm chairs in the Vatican offices, they probably do not understand truly to the very end what the war is," Archbishop Sviatoslav Shevchuk, the head of the Ukrainian Greek Catholic church, said on Thursday of the Vatican officials who organised the Good Friday event.

"We cannot talk about reconciliation now when they are killing us."

Archbishop Shevchuk said he appealed to the Vatican to change its plans.

Ukraine's government also expressed concern through its ambassador to the Holy See.

Some Ukrainians also see the event as potentially playing into Moscow's propaganda about Russians and Ukrainians being brothers that is used to imply they should be all part of one Russian nation.

Since the criticism erupted, the Vatican has tried to explain the gesture as a symbol of reconciliation and of the brotherhood between all Christians, and between Russian and Ukrainian peoples in particular.

Father Antonio Spadaro, a Jesuit and confidante of Pope Francis, said it was important to keep in mind that the Pope is "a shepherd, not a politician".

The Pope has actively tried to end or at least suspend the fighting, calling for an Easter truce and visiting Russian representatives at the Vatican.

Pope Francis has also spoken with Patriarch Kirill, the head of Russia's Orthodox Church and a staunch supporter of Mr Putin and of the invasion of Ukraine.

He may meet Patriarch Kirill in Jerusalem in June, according to Reuters.