Intercepted mobile phone calls show that Russian tanks and troops invaded before Georgia unleashed its offensive against South Ossetia, the Georgian government said Tuesday, pressing its claim that Russia was the aggressor in the war last month.

The recordings released Tuesday by the Georgian government aimed to turn the tables against Moscow in the battle for the moral high ground after a five-day war that killed hundreds of people and deepened the rift between Russia and the West.

Russia has always claimed that Georgia was the aggressor, saying it only responded militarily to defend Russian citizens and peacekeepers in South Ossetia.

Georgia said the recordings are phone calls between two South Ossetian border guards which prove that Russian tanks and troops entered South Ossetia many hours before the Georgian offensive began late Aug. 7.

The recordings were first released to The New York Times, which reported their contents Tuesday. A Georgian Interior Ministry official, Shota Utiashvili, played two of the recordings for The Associated Press and provided printed English translations from the original Ossetian.

Utiashvili said the alleged intercepts show "that Russian heavy armor entered Georgia about 20 hours before the war started."

"It again proves our case that Georgia's move was self-defense, rather than an unprovoked attack," he said.

The recordings are purportedly intercepts of two exchanges between a South Ossetian border guard at the southern entrance to the Roki tunnel, which leads from the separatist Georgian province to Russia, with another guard at the headquarters in the South Ossetian capital.

The northern tunnel entrance is in Russia.

Russian Foreign Ministry spokesman Andrei Nesterenko dismissed the Georgian claim as "not serious." He said any major troop movements would have been easily tracked by satellites used by NATO nations.

NATO's chief and ambassadors from all 26 allies were in Georgia on Tuesday, showing support for the pro-Western nation and demanding that Russia withdraw forces from Georgia in compliance with a cease-fire.

"I would be grateful if they provide such satellite data to us and the entire global community, provide specific data," Nesterenko said sarcastically. "Allegations that they have eavesdropped on someone and heard something are simply not serious."

According to the English translations of the recordings, in the first call, which purportedly began at 3:41 a.m. local time on Aug. 7, the South Ossetian guard at the tunnel says "they have moved armored personnel carriers out and the tunnel is full."

In the next call, about 10 minutes later, the guard says that "armor and people" had emerged from the tunnel about 20 minutes earlier. Asked whether there was a lot of armor, the guard says, "Well, tanks, BMPs and those things."

BMPs are armored personnel carriers. The tunnel is over 2 miles long.

Georgian President Mikhail Saakashvili has repeatedly said he was acting in self-defense when he ordered troops to open fire on Tskhinvali, the capital of South Ossetia. He has insisted there is evidence to back up his claim, but had not previously provided any details.

Utiashvili said Georgia provided the evidence to the United States and European governments and would welcome an investigation.

The authenticity of the recordings could not immediately be verified.

The New York Times said it had done its own independent translation of the audio files. The newspaper's translation was similar to the translation provided by Georgia, with slight differences that did not appear to change the meaning.

Russia has portrayed Saakashvili as a bloodthirsty, mentally unbalanced leader who was encouraged by the United States to use force to try to regain control over South Ossetia.

Western governments acknowledge that Georgia launched an offensive against the city of Tskhinvali but stress that Georgia was under increasing pressure amid growing Russian support for the separatist governments of South Ossetia and another breakaway province, Abkhazia. There had been frequent outbreaks of violence.

"The story that has been out there is that President Saakashvili is volatile and he launched this military conflict. I think that is a gross oversimplification of what really happened," the U.S. ambassador to NATO, Kurt Volker, told APTN on the sidelines of the NATO meetings Tuesday in Tbilisi, the Georgian capital.

Volker indicated he had not seen the specific evidence Georgia was presenting, but said the swift movement of a large Russian force into Georgia pointed to "advance planning" and said Russia had a yearslong policy of pressuring Georgia.

"No matter how we end up parsing out those few hours in the early morning of Aug. 7, Georgia was responding to a long period of Russian pressure, including violence that was going on, with shelling from South Ossetians," Volker said.

"(Georgia) made the decision to go into Tskhinvali, which was the trigger the Russians were looking for to launch this pre-planned invasion."