Heavy shelling on the outskirts of the eastern Ukrainian city of Donetsk threatens a delicate two-month-old ceasefire between Ukraine's government and pro-Russian separatists.

It's the heaviest shelling to hit the region in a month, and residents say they're afraid.

(SOUNDBITE) (Russian) DONETSK RESIDENT, YELENA, SAYING:

"It's scary. Of course, it's scary. All normal people who live here of course they are scared. It's really scary."

There have been no immediate reports of casualties, but explosions were seen and heard at Donetsk airport.

At least 4,000 people have died in conflict in Ukraine, and this latest round of shelling is unwelcome news for a shaky ceasefire that has been interspersed with violence over the last two months.