Clashes between Ukraine's army and pro-Russian rebels for control of a battered airport have intensified, with explosions and heavy gunfire shaking the area and at least six more people killed.

The battle for Donetsk airport in eastern Ukraine saw Kiev rush reinforcements to the snowy front lines on Saturday, while soldiers in the area spoke of some of the worst shelling yet in the nine-month war.

Fighting has flared in the region in recent days, with peace talks having stalled and a September truce in shreds.

"We try to hold on and to reciprocate," one Ukrainian soldier in Pisky, a few kilometres from the airport, told the AFP news agency.

"A lot of guys have already died. We have to end it all already, to stop it."

The blackened and wrecked shell of the airport has been repeatedly hit by heavy artillery in months of on-and-off clashes.

"The situation there is really difficult," military spokesman Andriy Lysenko said in a briefing.

"There are constant attacks and attempts to attack, but the military command constantly sends reinforcements."

He said three Ukrainian soldiers had been killed and 18 others wounded over the past day, bringing the military's toll to at least nine dead since Thursday.

At least eight civilians have been reported killed over the same period, including one on Saturday when rebels were accused of firing Grad rockets in the city of Popasna in the Luhansk region, according to regional governor Hennadiy Moskal.

A rebel official in Donetsk said that another two civilians were killed and five wounded in shelling that he blamed on Ukrainian forces.

Honey jar explosion

An elderly man identifying himself as a local resident in Stanicya Luganska handed soldiers at a checkpoint a three-litre jar of honey and thanked them for their service before walking away, said Moskal.

The jar later exploded, killing one soldier and seriously wounding three others.

As fighting rocked the area around the airport on Saturday, Lysenko also alleged that Russia was increasing its military presence along the Ukraine border.

He said arms including TOS-1 flamethrowers, C300 missile systems and Smerch and Hurricane rocket launchers had been spotted near the Russian city of Rostov-on-Don close to the border and were being periodically moved into Ukraine for attacks.

Russia, under Western sanctions over its actions in Ukraine, strongly denies sending weapons and troops into the war zone despite witness claims to the contrary.

More than 4,800 people have been killed in the conflict, while talks aimed at ending the fighting have stalled.