A comment attributed to President Vladimir Putin warning that Russia could capture Kiev in two weeks was taken out of context, his top foreign policy aide said Tuesday.

Moscow declared NATO a "threat" to its security Tuesday after the Western military alliance announced plans to reinforce defenses in eastern Europe because of Russia's alleged stoking of war in Ukraine.

Moscow's surprise declaration of a shift in its military doctrine came just ahead of a NATO summit in Wales on Thursday at which beleaguered Ukrainian President Petro Poroshenko will lobby U.S. President Barack Obama for military help.

U.N. Secretary-General Ban Ki-moon could include Lebanon in his tour to the region to discuss with Lebanese officials the situation in the country, An Nahar newspaper reported on Tuesday.

The daily said, however, that the issue hasn't been settled yet.

U.N. Secretary General Ban Ki-moon warned Western powers Tuesday "there is no military solution" to the Ukraine crisis, as NATO prepares to upgrade its combat readiness in eastern Europe.

Ban said he was greatly concerned at developments in Ukraine and wanted to avoid further deterioration in a crisis "that has been developing into a very chaotic and dangerous situation".

Poland's Prime Minister Donald Tusk warned on Monday that the war in eastern Ukraine risks spreading if NATO does not toughen its stance quickly.

Tusk, tipped as the European Union's next president, claimed that "our Western community is threatened by war, not just in eastern Ukraine", as Poles marked 75 years since the outbreak of World War II.

Ukraine's defense minister warned on Monday that a "great war" had broken out with Russia over his country's future that could claim tens of thousands of lives.

"A great war has arrived at our doorstep -- the likes of which Europe has not seen since World War II. Unfortunately, the losses in such a war will be measured not in the hundreds but thousands and tens of thousands," Valeriy Geletey wrote in a Facebook post.

Representatives of pro-Russian rebels in eastern Ukraine are seeking a special status for the region, a report said Monday, in what would constitute a de facto division of the country.

Spokesmen for the groups based in the eastern cities of Donetsk and Lugansk told Russia's Interfax news agency they were submitting a joint negotiating position in talks being held in Minsk on Monday.

Up to 15,000 Russian soldiers have been sent to Ukraine over the past two months, and at least 200 may have died in combat there, rights groups told AFP on Monday.

Moscow denies that it has deployed regular troops to Ukraine to prop up separatists battling Kiev forces, but multiple indications have emerged over the past weeks that Russian soldiers are on the ground in Ukraine.

Ukrainian forces were forced to retreat from Lugansk airport in the face of a Russian troop attack and Moscow soldiers moved into key cities in the east on Monday, Kiev said, a day after Russian President Vladimir Putin evoked "statehood" discussions for the conflict-torn east.

Putin accused Europe of ignoring the Ukrainian military's "direct targeting" of civilians in the conflict and said the offensive pushed by insurgents there were simply an attempt to expel Kiev's forces from residential areas.

Australia will toughen its sanctions against Russia over the crisis in Ukraine so they match those of the European Union, Prime Minister Tony Abbott said Monday.

Australia already has some sanctions against Russia, but Abbott said these would be tightened as a result of Moscow's persistent and deliberate violation of its neighbor's sovereignty.