But the Russians dispute that charge and on Wednesday said they were willing to make public a transcript and recording of the call. In effect, they plan to leak their own phone call.
Such leaks have played a conspicuous role throughout the conflict in Ukraine, implicating a whole cast of characters, including Western diplomats and shadowy pro-Russian separatists. Here's a look at how phone recordings have shaped our reading of Europe's most dangerous geopolitical conflagration in recent memory.
"F--- the E.U."
The recording that sparked the trend for leaked phone calls in the Ukraine crisis was notably vulgar. In the private phone call, audio of which was posted on YouTube in February, U.S. Assistant Secretary of State for European and Eurasian Affairs Victoria Nuland is heard cursing the European Union in a conversation with the U.S. ambassador to Ukraine, Geoffrey Pyatt. Nuland later confirmed the authenticity of the leak and apologized to E.U. officials.
At the time, the audio came as a shock. That phone calls of U.S. officials were apparently being recorded was, at this point, a surprise. But it also showed the split in the West's attitude to the Ukraine crisis, which had begun months before as a protest against President Viktor Yanukovych's U-turn on potential E.U. membership. As protests in Kiev turned violent, the United States grew increasingly impatient with Europe's slow response to the crisis.
"There is now stronger and stronger understanding that behind snipers, it was not Yanukovych, but it was somebody from the new coalition."
The next leaked call was released on YouTube a month later. In it, Estonian Foreign Minister Urmas Paet told E.U. foreign policy chief Catherine Ashton that there was speculation that the snipers who shot protesters in Kiev's Independence Square — popularly known as the Maidan — were agent provocateurs working to discredit the government. Ashton's response betrayed both her surprise and her Lancashire roots. "That's interesting," she told Paet. "Gosh."
The recording was trumpeted by pro-Kremlin media outlets, which saw it as an admission that the Euromaidan protests were a cynical coup and that accusations of excesses by Yanukovych were baseless. It would add to Russian distrust of the protests.
Although Ashton refused to comment on the leak, the Estonian Foreign Ministry admitted that the recording was genuine but that it only revealed Paet describing all he heard about the situation in Kiev. "We reject the claim that Paet was giving an assessment of the opposition's involvement in the violence," a statement from Estonia said.
"We should hit them with an atomic weapon."
In March, a recording that purported to show former Ukrainian prime minister Yulia Tymoshenko calling for violence against Ukraine's Russians appeared on YouTube. In the call with a former deputy secretary of Ukraine's National Security and Defense Council, Nestor Shufrych, Tymoshenko appears to suggest that the 8 million Russians living in Ukraine should be killed with nuclear weapons.
Tymoshenko, a star of 2004's Orange Revolution, had been released from prison after the Euromaidan protests, and she clearly hoped to play a big role. However, events moved on largely without her, and this leaked recording was only one reason why. Tymoshenko later took to Twitter to claim that the recording had been edited to discredit her. She included a message to those who she apparently thought were behind the leak, Russia's KGB successor: "Hello FSB :)"
"Write something like 99 percent down … well, not 99 percent … Let's say 89 percent voted for the Donetsk Republic."
In early May, Ukrainian security officials released a recording of an alleged phone call between a prominent rebel figure in eastern Ukraine and Alexander Barkashov, the leader of an ultranationalist paramilitary outfit in Russia with a clear fascist streak. In the call, Barkashov is purportedly advising his interlocutor in eastern Ukraine on how to proceed with an impending referendum, which led to the declaration by separatists of the "People's Republic of Donetsk." Just days later, a separatist election official in Donetsk told the news agency Reuters that nearly 90 percent had voted for independence. "Eighty-nine percent, that's it," he said.
Authorities in Kiev have long pinned the unrest and separatist insurgency in eastern Ukraine on Moscow. This recording appeared to indicate Russian collaboration and collusion with Ukraine's rebels.
"We have just shot down a plane."
The tragic crash of Malaysia Airlines Flight 17 in a picturesque wheat field in eastern Ukraine returned the world's attention to the conflict between Kiev's forces and pro-Russian rebels. Ukraine's security service leaked a recorded conversation purportedly between Igor Bezler, a pro-Russian rebel commander, and a supposed Russian intelligence official. They claimed that the call was made 20 minutes after the crash of MH17. Other leaked recordings surrounding the incident deepened convictions that pro-Russian rebels had been involved in shooting down the jet, which killed all 298 people aboard.
"Moscow asks where the black boxes are. They must be under our control."
Another recording leaked by Ukraine's security services allegedly revealed Moscow's direct hand in the aftermath of the MH17 crash. The recording supposedly was of Alexander Khodakovsky, a pro-Russian rebel commander, suggesting that friends across the border were desperate to take into their hands the plane's black boxes, which would have helped investigators piece together what happened to the plane.
Rick Noack contributed to this post.