Rockets killed civilians and soldiers deep in Ukrainian government-held territory on Tuesday and rebels pushed on with an assault to cut off an army-held rail junction, setbacks that showed Kiev's position worsening on the eve of peace talks.
Advances by pro-Russian rebels diminished hopes of a deal when Russia, Ukraine, France and Germany hold a summit in Minsk on Wednesday under a new Franco-German initiative to halt fighting in a war that has killed more than 5,000 people.
European officials say it is difficult to imagine the rebels agreeing to halt and go back to earlier positions after weeks during which they have been advancing relentlessly.