TALLINN, Estonia - There is a possibility the Russian government was involved in massive cyber attacks that have crippled Etonia's websites this month, the Baltic country's defence minister said Thursday.

The evidence is not enough to prove Russia played a role, "but it indicates a possibility,'' Defence Minister Jaak Aaviksoo told The Associated Press by telephone.

He said more than one million computers worldwide have been used in recent weeks to attack Estonian government and business websites since a dispute arose with Moscow over Estonia's moving of a Soviet-era war memorial from downtown Tallinn.

"We identified in the initial attacks IP numbers from the Russian governmental offices,'' Aaviksoo said, referring to Internet addresses that can be traced.

The attacks have also got the attention of NATO, which has sent a cyber expert to Estonia to help amid concerns that the military alliance might also be targeted, a NATO official said Thursday.

The Russian government has denied Estonia's accusations. Spokesman Dmitry Peskov said the attackers must have used a fake Kremlin Internet address to tarnish Russian authorities.

Aaviksoo said the attacks were massive and well-organized, targeting government offices and corporations, including the six major banks in the Baltic country.

"They started after we discovered instructions on Russian websites telling when, why and what to attack,'' he added.

Estonia, a country of 1.3 million people, is a European Union and NATO member as well as a key hub for Skype and other web pioneers.

The so-called "denial-of-service'' attacks against Estonian websites began after the April 27 removal of the Bronze Soldier, a statue commemorating Red Army soldiers killed fighting the Nazis. Estonia moved the statue from a downtown Tallinn square to a military cemetery outside the city.

Moscow said Estonia was desecrating the memory of Red Army soldiers, but many Estonians consider the statue a bitter reminder of five decades of Soviet occupation.

Estonia's Russian-speaking minority, who make up roughly one-third of the country's population and often complain of discrimination, also protested the move. The statue's move sparked the worst riots in Estonia since it left the Soviet Union in 1991.

NATO's systems in Estonia have not been attacked, but officials were on the alert since attacks against one NATO member are considered an assault on the whole alliance, said the NATO official, who spoke on condition of anonymity.

The cyber controversy is expected to surface at an EU-Russia summit this week in Samara, southeast of Moscow.