“Our state will insist on international reconnaissance,” he said. “It is obvious that the Russians are playing with the lives of Ukrainian prisoners, with the feelings of their relatives and with the emotions of our society.”

An Ilyushin Il-76 aircraft crashed in the Belgorod region of western Russia on Wednesday. According to Russian reports, all 74 people on board were killed – including 65 Ukrainian prisoners of war.

However, there is still no independent information on who or what the aircraft was carrying.

The Russian Defence Ministry accused Ukrainian forces of shooting down the plane as it passed over Russia’s Belgorod region near the Ukrainian border.

“All occupants on board have died,” Belgorod governor Vyacheslav Gladkov said.

Moscow said the Ukrainians were being taken to a planned prisoner exchange.

Ukraine later confirmed following the crash that an exchange of prisoners of war had been planned for Wednesday.

“An exchange of prisoners should have taken place today, but it did not,” the HUR said in the early evening.

Kyiv did not confirm the version from Moscow that the Ukrainian prisoners were on board the crashed Russian plane and are now dead.

Instead, the statement said: “We currently have no reliable and comprehensive information about who exactly and how many were on board the aircraft”.

For its part, Ukraine had honoured all agreements and brought the Russian soldiers to the exchange location on time, the secret service said.

It continued: “According to the agreement, the Russian side had to ensure the safety of our defenders. At the same time, the Ukrainian side was not informed about the need to ensure the security of the airspace in the area around the city of Belgorod in a certain period of time, as was done several times in the past”.

The fact that Ukraine was not informed of the exact Russian means of transport this time “could indicate deliberate actions by Russia aimed at jeopardising the lives and safety of prisoners,” the Ukrainian authorities wrote.

Russian state media interpreted the communication as indirect confirmation that the Ukrainians had shot down the aircraft with their own soldiers on board. However, there is no official confirmation of this from Kyiv.

Footage circulating on social media purportedly showed the moment of the crash, with a fireball seen in the distance and then a huge black cloud rising into the sky.

The plane was said to have gone down about 50km northeast of Belgorod city and around 50km from the Ukrainian border.

The Russian Defence Ministry and other officials quickly pointed the finger at Ukraine.

“The Ukrainian leadership was well aware of the planned prisoner exchange and was informed about how the prisoners would be transported,” said Andrei Kartapolov, head of the State Duma’s defence committee in Moscow.

A total of 192 Ukrainians were to be exchanged for 192 Russian prisoners, he said, with to operation to have involved three transport planes. The exchange has now been called off, he said.

Without providing evidence, Kartapolov said that the plane had been shot down by three US or German anti-aircraft missiles.

Ukrainian officials have yet to confirm or deny Russia’s claims about the crash, and there were contradictory reports in the local media.

The news portal Ukrainska Pravda (Ukrainian Truth) cited military sources as saying that the Ukrainian side had confirmed the crash.

According to information from the General Staff cited by the report, the Russian aircraft was carrying S-300 anti-aircraft missiles to the front line.

Originally, Ukrainska Pravda had also reported that the Ukrainian military had spoken of the aircraft being shot down. This version was then changed.

The Ukrainian coordination centre for prisoners of war did not comment on the incident. All information is being collected and analysed, the centre said on Telegram.

Ukraine has been fending off a full-scale Russian invasion for almost two years: Wednesday marked the 700th day of war.