DONETSK, Ukraine — Separatist forces in eastern Ukraine said Wednesday they have almost fully encircled government forces in a town that hosts a strategic railway hub, putting them within grasp of a decisive new victory.

Eduard Basurin, the deputy commander of the separatist forces, said the highway linking the town, Debaltseve, to other government-held areas has now fallen into rebel hands. The encirclement of the town has not, however, been fully executed, Basurin said.

Ukrainian military spokesman Andriy Lysenko confirmed Debaltseve is surrounded on two flanks and is being heavily targeted with Grad multiple rocket launchers. Other officials denied government forces were close to folding and said separatist claims were exaggerated.

Debaltseve is one of multiple flashpoints that have flared up across eastern Ukraine since the start of the month.