Four Ukrainian troops were killed as forces carried out over 100 attacks on rebel positions and forced pro-Russia separatists out of three eastern villages, a military official said Wednesday.

The foreign ministers from Germany, France, Ukraine and Russia were to meet later Wednesday in Berlin to keep searching for a way to de-escalate the conflict that has taken over 400 lives since April.

Fighting in eastern Ukraine has increased since a much-violated 10-day cease-fire expired Monday. President Petro Poroshenko said conditions for further peace talks had not been met as rebels refused to disarm or hand back seized border posts.

National Security and Defense Council spokesman Andriy Lysenko said three military troops died in rebel attacks on government vehicles and checkpoints and 10 were wounded.