In a report to be published in its Monday edition, OSCE military observers in the Caucasus described detailed planning by Georgia to move into South Ossetia which contributed to the crisis, the German magazine said.
The report also backed up Russian claims that the Georgian offensive was already in full swing by the time Russian troops and armored vehicles entered the Roksky Tunnel, on the border with Russia and South Ossetia, to protect its peacekeepers and the civilian population.
The OSCE report also contains suspected war crimes committed by Georgians, who ordered attacks on sleeping South Ossetian civilians.
Georgia attacked South Ossetia on August 8 in an attempt to regain control over the separatist republic, which split from Tbilisi in the early 1990s.
Most people living in South Ossetia have Russian citizenship and Moscow subsequently launched an operation to "force Georgia to accept peace." The operation was concluded on August 12.
Russian President Dmitry Medvedev signed decrees Tuesday recognizing South Ossetia and Abkhazia as independent states and called on other countries to follow suit.
Russia has accused Georgia of committing "genocide" by launching the offensive in South Ossetia. Russia is calling for an international war crimes trial for the Georgian leadership, which Moscow says is responsible for massive loss of life in South Ossetia.