"They have returned in the direction of Donetsk", justice ministry spokesperson Sentina van der Meer said. "Explosions were heard, and they were warned by the locals."
The Ukrainian military earlier said its forces were battling pro-Russian rebels for control of several eastern Ukrainian towns around the crash site of the downed Malaysia Airlines plane.
Ukrainian troops "had entered" the towns of Shakhtarsk and Torez and "battles were continuing for the complete liberation" of the towns of Pervomaysk and Snizhne, the press office for the military operation against the insurgents said.
A joint Dutch and Australian forensics team had left from rebel stronghold Donetsk early on Monday in a fresh bid to reach the crash site, where some remains of victims remain exposed to the elements.
A visit on Sunday was cancelled after heavy bombardments rocked towns nearby.