By Zeba Siddiqui

SAN FRANCISCO, June 22 (Reuters) - Russian government hackers have conducted multiple cyber spy operations on countries allied with Ukraine since Moscow's February invasion of that country, Microsoft said in a report on Wednesday.

"The cyber aspects of the current war extend far beyond Ukraine and reflect the unique nature of cyberspace," Microsoft President Brad Smith said in the report.

The Russian embassy in Washington did not immediately respond to a request for Office 365 comment.

Moscow has in the past denied conducting foreign cyber espionage missions, saying it "contradicts the principles of Russian foreign policy."

Researchers had already traced a series of destructive cyberattacks on Ukrainian entities to Russian state-backed hacking groups since the conflict began.

The Microsoft report said researchers found 128 organizations in 42 countries outside Ukraine were also targeted by the same groups in stealthy, espionage-focused hacks.

Outside Ukraine, the United States was the country most-targeted by such intrusion efforts, the report said, but member countries of the military alliance NATO - which has provided critical support to Ukraine amid the conflict - were hit too.

These include organizations based in Denmark, Latvia, Lithuania, Norway and Poland, as well as Finland and Sweden, countries that have voiced a desire to join the NATO alliance.

"The target appeared to be mostly governments, although also included think tanks, humanitarian groups, and critical infrastructure providers," the report said.

Microsoft said the hacking against allies was successful about 29% of the time and in some cases led to data being stolen.

Foreign policy experts say they fear Russia´s combined kinetic and cyber warfare strategy against Ukraine will become a model for future conflicts.

In an earlier report, Microsoft indicated cyberattacks - which involved data wiping malware - laid the groundwork for military missions in Ukraine.

The latest research cited six incidents since the invasion when cyberattacks against targets in Ukraine appeared to precede military attacks.

In one, it said Russian hackers tried to breach a Ukrainian nuclear power company´s computer network a day before Russia´s army occupied the company's largest plant.

Russia calls the invasion a "special operation" to root out "Nazis." Kyiv and the West call that a baseless justification for a war to wipe out Ukraine's identity as a separate nation. (Reporting by Zeba Siddiqui; Editing by Chizu Nomiyama and Howard Goller)