Ukrainian forces killed five rebels today while repelling an attack by 500 pro-Russian gunmen on a federal border guard camp in the strife-torn separatist east, Kiev officials said.
The border guard service said seven of its servicemen were wounded when "around 500 terrorists" attacked one of its units stationed outside the industrial city of Lugansk.
The rebels are "not only using mortar, grenade launchers and machine guns, but also firing from residential apartments and rooftops, using civilians as human shields," the border guard service said in a statement.
A spokesman for Ukraine's self-proclaimed "anti-terrorist operation" said the border guards eventually received air cover from fighter bombers that managed to destroy "two mortar crews of militants".
"After the aircraft returned to base, we received information that fighting around the Lugansk border unit resumed," Vladyslav Seleznyov told Kiev's ICTV television.
Ukraine's defence ministry said on Friday that the seven-week eastern insurgency had claimed the lives of 49 Ukrainian servicemen and 128 civilians and separatists.
Russia has accused Ukraine of breaching the 1949 Geneva Conventions protecting civilians in wartime by killing peaceful citizens.
It piled further diplomatic pressure on Kiev by announcing that it would submit a draft resolution to the United Nations Security Council later today, demanding an immediate end to fighting and the creation of a corridor that would allow civilians to escape the affected areas.
Ukraine has previously rejected the need for such an "aid corridor" out of fear that Russia might want to send in troops to supervise the evacuation.