Ukraine said Russian forces had crossed the border and were supporting separatist attacks. The US State Department said it suspected a Russian-directed counter-offensive was under way. Russia has repeatedly denied arming or covertly supporting the rebels.
Reporters say the suspicion is that Moscow is opening a new front to divert Ukrainian forces from the besieged cities of Donetsk and Luhansk, where they have made significant advances against pro-Russian separatists.
Earlier on Wednesday, the mayor of the Ukrainian port of Novoazovsk on the Sea of Azov said rebel tanks and armored vehicles had entered the town. Rebels have been trying for weeks to break out of an area further north in the Donetsk region where they are almost encircled.
Analysts say the separatists could also be seeking a land link between Russia and Crimea, which also would give them control over the entire Sea of Azov.
The reports of renewed fighting came just hours after Ukrainian President Petro Poroshenko promised a roadmap for peace in the east. He spoke after holding his first direct talks on the crisis since June with Putin.
The US also expressed its "deep concern" at the latest developments.
reporter
Park Sae-jin
swatchsjp@ajunews.com
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