While the Iranian government has admitted that a unit of the Iranian Revolutionary Guards fired on the plane, it did so only after three days of stonewalling. And even then, President Hassan Rouhani insisted that the truth had been concealed from him and other members of the elected government by the air defense unit of the Revolutionary Guard Corps.

In an interview with Ukrainian media, President Zelensky claimed that the exchange captured on the tape made clear that Iranian authorities knew almost immediately that a missile had brought down the plane, though the air traffic controller is the only government worker heard on the audio tape. He did not provide any evidence that the controller quickly shared that information with government officials.

Mr. Zelensky did not directly contradict the Iranian government’s claim that it had been kept in the dark, but he noted that even the military — which knew what had happened — continued to issue false statements. Those included a claim that the crash had been caused by mechanical problems. That, he said, showed a broad effort to suppress the truth in those first three days.

“We understood that the Iranians — we were not sure exactly who — but they wanted to defend themselves in such an unlawful way, by pushing information that it was a technical flaw,” Mr. Zelensky said.

The recording begins a few minutes after Ukrainian Flight 752 took off from Imam Khomeini Airport in Tehran on Jan. 8.