Ukrainian forces have launched an “all-out attack” against rebels west of Donetsk, according to the country’s interior ministry.
It said the attack was targeting “several parts of the front” near Donetsk and the neighbouring city of Lugansk.
A team from the AFP news agency about 18 miles from Donetsk reported hearing the echoes of heavy artillery fire.
The Ukrainian military had recently warned of a “nasty surprise” for separatists holed up in the city of 900,000.
Ukrainian government forces have recently gained the ascendencyin the three-month-long conflict with pro-Russian separatists in the east of the country.
The rebel stronghold of Slavyanskis now back under government control after a military operation at the weekend – a major victory for the Kiev authorities.
Many rebels reportedly fled from there to Dontesk.
More than 200 government troops and hundreds of rebels have been killed since the unrest began.
Three more Ukrainian soldiers died on Wednesday, said military spokesmanVladyslav Seleznyov.
One was killed when a convoy was ambushed near Luhanskand two others died when their personnel carrier was blown up by a landmine in the village ofChervonaZorya, near Donetsk