Intercepted phone calls purportedly between Russian military intelligence officers and members of a pro-Russian separatist group that appear to capture the moment the rebels realized the plane they shot down was a civilian passenger plane could be the smoking gun that helps prove Malaysia Airlines Flight 17 was downed Ukraine by the insurgents.

The tapes were released by SBU, Ukraine's security agency, and transcript was published in the Kiev Post. It appears to capture the chaotic moments after the plane was shot down — and the realization that it was a passenger plane rather than a Ukrainian transport plane, which had been targeted in recent days by the Russia-backed separatists.

"We have just shot down a plane," says a man the SBU identified as Igor Bezler, a Russian military intelligence officer and leading commander of the self-proclaimed Donetsk People’s Republic.

That call came just 20 minutes after the crash and was placed to a person identified by Ukraine’s SBU as a colonel in the main intelligence department of the general headquarters of the armed forces of the Russian Federation Vasili Geranin, according to Ukraine security officials.

But in a second tape released by the agency, two men identified as "The Greek" and "Major" discuss the debris field and the fact the the plane was a civilian aircraft.

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“It’s 100 percent a passenger [civilian] aircraft,” Major is recorded as saying, as he admitted to seeing no weapons on site. “Absolutely nothing. Civilian items, medicinal stuff, towels, toilet paper.”

The Boeing 777 was flying from Amsterdam to Kuala Lumpur when it was shot down by what U.S. intelligence sources confirm was a surface-to-air missile near the village of Chornukhine, Luhansk Oblast, some 30 miles inside the the border with Russia.

The second conversation, if verified as authentic, could dispel Russian separatist claims that it was the Ukrainian military that shot the plane down. According to the transpcript:

Major: "These are Chernukhin folks who shot down the plane. From the Chernukhin check point. Those cossacks who are based in Chernukhino."

Grek: "Yes, Major."

Major: "The plane fell apart in the air. In the area of Petropavlovskaya mine. The first '200' [code word for dead person]. We have found the first '200.' A Civilian."

Greek: "Well, what do you have there?"

Major: "In short, it was 100 percent a passenger [civilian] aircraft."

Greek: "Are many people there?"

Major: "Holy [expletive]! The debris fell right into the yards [of homes]."

In a third intercepted conversation released by the SBU — which the agency says took place about 40 minutes after insurgents seemed to realize they had shot down a civilian plane — Cossack commander Nikolay Kozitsin tells an unidentified separatist that the fact the Malaysia Airlines plane was flying over the combat zone likely meant it was carrying spies.

"That means they were carrying spies," Kozitsin allegedly says. "They shouldn’t be [expletive] flying. There is a war going on."

On Friday, emergency workers combed the sunflower fields and villages of eastern Ukraine, searching the wreckage of the jetliner. The attack on Thursday afternoon killed 298 people from nearly a dozen nations, including vacationers, students and a large contingent of scientists heading to an AIDS conference.

U.S. intelligence authorities said a surface-to-air missile brought down Malaysia Airlines Flight 17 as it flew from Amsterdam to Kuala Lumpur, but could not say who fired it. The Ukraine government in Kiev, the separatist pro-Russia rebels they are fighting in the east and the Russia government that Ukraine accuses of supporting the rebels all deny shooting the passenger plane down. Moscow also denies backing the rebels.

By midday, at least 181 bodies had been located, emergency workers said.

Russian President Vladimir Putin blamed Ukraine for the downing, saying it was responsible for the unrest in its Russian-speaking eastern regions — but did not accuse Ukraine of shooting the plane down and did not address the key question of whether Russia gave the rebels such a powerful missile.

Ukrainian Prime Minister Arseniy Yatsenyuk described the downing as an "international crime" whose perpetrators would have to be punished in an international tribunal.

The Associated Press contributed to this report.