Ukraine says its troops make breakthrough in rebel stronghold

Ukrainian servicemen search for explosives with a sniffer dog around a checkpoint near the eastern Ukrainian town of Debaltseve, August 16, 2014. REUTERS/Valentyn Ogirenko

KIEV/DONETSK Ukraine (Reuters) - Ukrainian forces have raised their national flag over a police station in the city of Luhansk that was for months under rebel control, Kiev said on Sunday, in what could be a breakthrough in Ukraine's efforts to crush pro-Moscow separatists.

Ukrainian officials said, however, the rebels were fighting a desperate rearguard action to hold on to Luhansk - which is their supply route into neighbouring Russia - and that the flow of weapons and fighters from Russia had accelerated.