Russian officials said Sunday that Moscow is still awaiting official confirmation from Ukraine that a planned exchange of 6,000 bodies of soldiers killed in action will take place, reiterating allegations that Kyiv had postponed the swap.

On the front line in the war, Russia said it pushed into Ukraine’s Dnipropetrovsk region.

Russian state media quoted Lt. Gen. Alexander Zorin, a Russian negotiating group representative, as saying Russia delivered the first batch of 1,212 bodies of Ukrainian soldiers to the exchange site at the border and is waiting for confirmation from Ukraine, but there were “signals” that the process of transferring them would be postponed until next week.

Citing Zorin on her Telegram channel, Russian Foreign Ministry spokesperson Maria Zakharova asked whether it was Ukrainian President Volodymyr Zelenskyy’s “personal decision not to take the bodies of the Ukrainians” or whether “someone from NATO prohibited it.”

Ukrainian authorities said plans agreed upon during direct talks in Istanbul on June 2 were proceeding accordingly, despite what Ukraine’s intelligence chief, Kyrylo Budanov, called Russian attempts to “unilaterally dictate the parameters of the exchange process.”

“We are carefully adhering to the agreements reached in Istanbul. Who, when and how to exchange should not be someone’s sole decision. Careful preparation is ongoing. Pressure and manipulation are unacceptable here,” he said Sunday in a statement on Telegram.

“The start of repatriation activities based on the results of the negotiations in Istanbul is scheduled for next week, as authorized persons were informed about on Tuesday,” the statement said. “Everything is moving according to plan, despite the enemy’s dirty information game.”

Vladimir Medinsky, an aide to Russian President Vladimir Putin, led the Russian delegation. Medinsky said Kyiv called a last-minute halt to an imminent swap. In a Telegram post on Saturday, he said that refrigerated trucks carrying more than 1,200 bodies of Ukrainian troops from Russia had already reached the agreed exchange site at the border when the news came.

In other developments, Russia’s Defense Ministry said Sunday that its forces had reached the western edge of the Donetsk region, one of the four provinces Russia illegally annexed in 2022, and that troops were “developing the offensive” in the neighboring Dnipropetrovsk region. This would be the first time Russian troops had pushed into the region in the more than three-year-old war. Ukraine didn’t immediately respond to the claim, and The Associated Press couldn’t immediately verify it.

One person was killed and another seriously wounded in Russian aerial strikes on the eastern Ukrainian Kharkiv region.

Russian authorities said early Sunday that two international airports serving Moscow temporarily suspended flights because of a Ukrainian drone attack. Later in the day, one airport halted flights temporarily for a second time, along with a third airport.