Three Ukrainian civilians have died overnight in mortar fire around Donetsk airport, where government forces held out against pro-Russian rebels in the latest deadly violation of a ceasefire.
Local officials said the clashes, in which five people were wounded, lasted nine hours.
A Ukrainian military spokesman said government troops remained in control of the surrounding area, which was briefly seized by rebels in May and then recaptured.
A truce in the six-month conflict signed on 5 September has calmed some of the tension.
However, military forces continue to mount daily raids on the international airport, which was once the busiest in eastern Ukraine.
Its runway could enable the separatists to receive essential supplies from Russia.
The conflict has so far claimed about 3,400 lives and raised security concerns across eastern Europe.
The Kremlin denies leading the conflict in reprisal for the new Ukrainian leaders' decision to pull the ex-Soviet country out of Russia's orbit and align it with the West.
But NATO has reported the movement of Russian tanks and special forces into the war zone and Ukraine claims to have arrested Russian agents in the region.
The United Nations' human rights office said that continuing clashes have killed more than 300 people since the ceasefire agreement, although the Ukrainian government has only reported 115 deaths.
