Russia has strongly condemned repatriation from Turkey of several Ukrainian commanders who were supposed to remain there until the end of the war under an agreement between Moscow and Kiev.
The five commanders belonged to Ukraine's ultranationalist Azov Battalion, who were freed in a prisoner swap deal last September and taken to Turkey. The swap involved almost 300 people, including 10 foreigners, which made it the largest exchange since the start of the Ukrainian conflict.
Ukraine, for its part, sent back 55 Russians and also released pro-Moscow Ukrainian opposition leader, Viktor Medvedchuk.
On Saturday, the commanders returned to Ukraine alongside Ukrainian President Volodymyr Zelensky, who was on a visit to Turkey.
This is while the deal between Kiev and Moscow stipulated that they should stay there until the end of the war in Ukraine.
"The return of Azov commanders from Turkey to Ukraine is nothing but a direct violation of the terms of existing agreements," Kremlin spokesman Dmitry Peskov was quoted as saying by Russian news agencies.
He added that both Ukraine and Turkey had violated the terms of the agreement, as Russia had not been informed of their release.
"No one informed us about this. According to the agreements, these ringleaders were to remain on the territory of Turkey until the end of the conflict," the Kremlin spokesman said.
Peskov attributed the commanders' return to the failure of a counteroffensive that was recently launched by Ukraine as a means of pushing back against Russian troops.
He also linked Turkey's violation of the deal to the country's desire to show solidarity with other members of NATO ahead of a summit of the US-led military alliance that is slated to be held in the Lithuanian capital city of Vilnius on July 11-12.
"Preparations for the NATO summit are underway and of course there has been a lot of pressure on Turkey," he said.