Estonia is accusing Russia of waging cyber war against it by launching massive attacks on computer systems in the Baltic republic.

In an interview with The Times, Urmas Paet, the Estonian Foreign Minister, accused the Kremlin of direct involvement in attempts to paralyse Estonian government websites and telephone networks as part of a campaign of unofficial sanctions.

The attacks involve launching tens of thousands of visits to websites with the intention of overloading their servers and forcing the computers to crash. Estonian experts have traced the internet protocol (IP) addresses that identify individual computers back to systems used by Russian authorities, including some in the presidential administration.

"When there are attacks coming from official IP addresses of Russian authorities and they are attacking not only our websites but our mobile phone network and our rescue service network, then it is already very dangerous," Mr Paet said.

"It can cost lives. I hope they will stop it but the attacks are continuing. They are sending huge levels of stuff through the networks so that our different servers will crash.

"The largest part of these attacks are coming from Russia and from official servers of the authorities of Russia."

Cyber-terrorism experts from Nato are now in Estonia's capital Tallinn to study the impact of the attacks, which have caused alarm across the military alliance. The issue is also expected to be raised at a summit between Russia and European Union leaders tomorrow.

Estonia's second-biggest bank, the Swedish-owned SEB Eesti Uhispank, said it came under "massive cyber-attack" on Tuesday. It has been forced to block access to its online banking services from outside Estonia in an effort to prevent the attacks crashing its servers.

Other targets have included the websites of Estonia's president and parliament as well as most government ministries and political parties. Three of the republic's news organisations have also been affected, as have banks and communications services.

The cyber attacks began after the Estonian authorities moved a Second World War monument to the Red Army from the centre of the capital Tallinn to a military cemetery in a suburb of the city last month.

Estonians regard the Bronze Soldier statue as a monument to 50 years of occupation by the Soviet Union. But Moscow reacted furiously, accusing Estonia of insulting the memory of millions of Soviet soldiers who died in the fight against Nazi Germany.

Sergei Lavrov, the Russian Foreign Minister, accused the EU and NATO of "conniving" with countries that had made a mockery of history. The removal of the statue also triggered Estonia's worst riots since independence in 1991 as members of the country's Russian minority, who make up a quarter of its 1.3 million people, reacted angrily.

Kadri Liik, director of Tallinn's International Centre for Defence Studies, said that relations with Russia were at their worst since independence and that Moscow was reacting very emotionally in seeking ways to punish Estonia.

"For Estonia, it would be unpleasant to have a permanent battle with Russia and to ask for help from the EU and Nato. We have spent quite a bit of political capital already asking for their help," she said.

"We tried to solve it internally but when Russia's hand became so visible we had to make clear that this is not an everyday exchange of unpleasantries between Estonia and Russia. This is serious and please understand it.

"Russia is clearly testing Nato and the West. It is a cynical approach, they see how NATO is divided on many issues and that the US is bogged down in Iraq and they are just flexing their muscles."

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