Fierce fighting continues in eastern Ukraine, with Kyiv claiming it now has the upper hand against pro-Russian separatists.
The government said it is pressing forward in the key city of Luhansk which has been under rebel control for months.
Ukrainian troops have been closing in on Luhansk from the outskirts, but have not previously been able to get forces inside the city limits.
A photograph posted on Twitter appeared to show a Ukrainian flag being placed on the front of the police station in the Zhovtneviy neighbourhood of the city. The picture could not be independently verified.
The separatists, who still control sections of the border linking Luhansk region to Russia, have responded to the reverses with defiant rhetoric and the fighting continues.
Ukrainian officials allege they have pushed the separatists out of large swathes of territory, nearly encircled them in their strongholds of Donetsk and Luhansk, and now have taken control the road between the two cities
But they say supplies are still coming in from neighbouring Russia.
Andriy Lysenko, a spokesman for the National Security and Defence Council of Ukraine, told reporters: “We have information that rebels used their routes, which are not under the control of the Ukrainian army, and got some ammunition and troops that came across from the Russian Federation. We can’t say the exact numbers, we’re checking this information.”
As Kyiv’s troops set up checkpoints in newly recaptured areas, Alexander Zakharchenko, prime minister of the self-proclaimed Donetsk People’s Republic, said over the weekend that rebels were in the process of receiving some 150 armoured vehicles, including 30 tanks, and 1,200 fighters trained in Russia to launch a major counter-offensive.
The assertion that the fighters were trained in Russia is awkward for Moscow. The Russian government has repeatedly denied allegations from Kyiv and its Western allies that it is providing material support to separatist fighters.