Four Ukrainian troops were killed as forces carried out more than 100 attacks on rebel positions and forced pro-Russian 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 more than 400 lives since April. Fighting in eastern Ukraine has increased since a much-violated 10-day cease-fire expired Monday. Ukrainian 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. The federal border guards said one guardsman was killed when the Novoazovsk crossing point came under attack by rebels with mortars in the Donetsk region.
Donetsk is one of two eastern regions that have declared independence from the government in Kiev.
Border posts have become a key issue, since Ukraine and the U.S. say military equipment and reinforcements are flowing across the border from Russia, something Russia denies.
Ukraine says it recaptured a key border post Tuesday at Dovzhanskiy, which rebels had mined with explosives. That crossing is one of three that Poroshenko had unsuccessfully demanded that the rebels return.
In Berlin, German Chancellor Angela Merkel said she "cannot rule out that we will have to go further" in imposing sanctions on Russia.
The EU and the U.S. have already imposed targeted sanctions mostly hitting individual officials in Russia and have held off on more costly sanctions on entire industries.
"We will not let up … in seeking diplomatic solutions to the conflict, but we are still far from where we would like to be," she said after meeting with NATO Secretary General Anders Fogh Rasmussen.