Online attacks must be treated like conventional military assaults, authorities said Wednesday in Estonia, which fell victim to a "cyber-war" in 2007.

"Estonia supports, and has since the 2007 attacks advocated, the principle that cyber and physical attack would be treated on the same conceptual basis," Defence Minister Mart Laar told AFP, after Washington said it would respond to hostile acts in cyber-space as it would to any other threat.

"If cyber-attacks create substantial economic damage, disruption of the functioning of society and human losses, they should be handled as a matter of national security and we should react accordingly," Laar added.

Estonia, a nation of 1.3 million, has put itself at the forefront of cyber-defence in part because it is home to a flourishing IT sector but also because of bitter experience.

In 2007 Estonian official and bank websites were taken down by blistering attacks.

The assault was widely blamed on Russian hackers, although Moscow rejected claims of official involvement.

Estonia is also home to the cyber-lab of NATO -- it joined the trans-Atlantic alliance in 2004, 13 years after independence from the Kremlin -- which next week hosts an international conference of IT defence experts.

In cyber-warfare, aggressors are often hard to identify and hence may not fear immediate retaliation -- a key plank of conventional warfare.

But Laar said that was no reason not to adopt a clear strategy.

"We should determine our response to an attack based on the damage it causes or was intended to cause, not the type of weapon employed," he said.

"Depending on the nature and scale of the attack, the response to it would include a wide range of possible options, including military," he added.

Last week, Laar urged fellow NATO members to be "more ambitious" about cyber-defence.

This was underlined by senior Estonian lawmaker Mati Raidma, who heads the country's defence committee, on Wednesday.

"Because NATO is a collective organisation, cyber-attacks against one state should be really seen as cyber-attacks against the whole of NATO," he said.