Civilians in Donetsk are reported to be fleeing after the pro-Russian rebel-held city was hit by artillery fire during an advance by Ukrainian forces into the area.
Residents in the outskirts of Donetsk said that they witnessed shelling on Tuesday for the first time since separatists took control over the city. Clashes also reportedly erupted in the centre between rebels and an unidentified group, which appeared to be part of Ukraine's security forces.
A Reuters reporter at the scene said they witnessed an intense gunfight erupting in the centre of Donetsk, in which about six rebel gunmen were hiding behind cars in a parking lot of a mall, running and firing at another group of people.
The fighting came as the Ukrainian military said it had recaptured parts of the rebel-held city of Luhansk, near the Russian border, which has been besieged by security forces for weeks, and a strategic town near Donetsk.
Almost 350,000 people have been forced to flee their homes and more than 2,000 others have been killed in eastern Ukraine due to fighting between government troops and rebels.
Meanwhile, Russian president Vladimir Putin and his Ukranian counterpart Petro Poroshenko, who have not met since early in June, plan to meet next week in Belarus with EU representatives and the Eurasian Customs Union, the Kremlin said on Tuesday.
Poroshenko's office said the leaders would use the August 26 meeting to discuss ways to stabilise the conflict in eastern Ukraine, as well as energy security and Kiev's new trade deal with the EU, which Moscow has opposed.
Meanwhile, the Ukrainian army says it has recovered fifteen bodies from the site of Monday's rocket strike on a refugee convoy of buses and cars in eastern Ukraine. The attack occurred near Luhansk.