NATO chief arrives in Ukraine as crisis in the east deepens

NATO Secretary-General Anders Fogh Rasmussen, who met with leading officials in Ukraine on Thursday, said that the military alliance stood ready to support Ukraine with advisers and assistance.

Ukraine is not a member of the 28-nation alliance, and both sides say that Kiev joining the organization is not on the cards.

While stopping short of committing to direct assistance in Ukraine's ongoing conflict, Rasmussen said that NATO would intensify its cooperation with Ukraine on defense planning and reform. His visit comes as tensions rise over an alleged Russian troop buildup along its ex-Soviet neighbor's border.

The meeting also comes a day after Ukrainian forces carried out their first air strike on the pro-Russian rebel stronghold of Donetsk, as they said they were preparing to take back the city, although they also reported their highest death toll in weeks in the face of fierce rebel bombardments.

One person was killed and two injured on Thursday when a hospital was hit by shelling, local health authorities said.

"Today as a result of a mortar shell hitting the ... first Donetsk city hospital, one person died and two were injured," the regional health administration said in a statement, adding that no medics were among the casualties. 

Overnight shelling killed three people and wounded five as government forces tightened their grip on Donetsk, the city council said on Thursday.

NATO on Wednesday accused the Kremlin of bolstering its troop numbers on the Ukraine border to 20,000, from 12,000 in mid-July, creating a "dangerous situation" and stoking concerns Moscow could intervene in its neighbor by force.

"We share the concern that Russia could use the pretext of a humanitarian or peacekeeping mission as an excuse to send troops into eastern Ukraine," NATO spokeswoman Oana Lungescu said.

Donald Tusk, Poland's prime minister, said “the threat of a direct intervention [by Russia into Ukraine] is certainly greater than it was even a few days ago.”

German Chancellor Angela Merkel called on Russian President Vladimir Putin to use his influence with the separatists for the "stabilization" of Ukraine. Moscow said those making the claims about their troop movements were “selling soap bubbles.”

Russia denies that it had increased the number of its troops on the border.

"Movements of such forces of thousands of troops and equipment are not possible in such a short time," said Russian defense ministry spokesman Igor Konashenikov.

The United States and European Union have slapped a range of tough sanctions on Moscow, with Switzerland, Japan and Canada following suit, potentially pushing Russia's fragile economy towards recession.

Putin struck back on Wednesday with import bans and restrictions on farm products from countries that have targeted Moscow.

NATO has consistently backed up Kiev's allegations that Moscow has fomented and armed pro-Russian rebels battling government troops in eastern Ukraine for almost four months.

The U.N. says the fighting in eastern Ukraine has killed more than 1,300 people and forced some 285,000 people to flee their homes.

Rasmussen recently ratcheted up the rhetoric over Ukraine, saying in an interview published on Sunday that NATO would draw up new defense plans in the face of "Russia's aggression."

Elsewhere in the capital Kiev, clashes erupted as city authorities sought to clear away the remnants of a tent colony erected by demonstrators involved in the street uprising against pro-Russia President Viktor Yanukovych. At the time, protesters were angry about endemic corruption and wanted closer ties with the European Union.

In scenes reminiscent of that revolt, which climaxed with Yanukovych's ouster in February, demonstrators set tires on fire in their face-off against a volunteer battalion overseeing the clean-up operation.

Wire services