A 450-mile railway line Russia is building through occupied Ukraine is almost complete, Kyiv’s military intelligence chief has warned.

“Russia has actually been building a railway for over a year now to connect with our temporarily occupied southern territories. This process is almost complete, and it could pose a serious problem for us,” Kyrylo Budanov told Ukrainian state television.

The intelligence chief added that he assumes Ukraine will be able to cope with the issue, but did not provide any further details.

“I hope that we will somehow manage the land section of the railway,” he said. “Everyone has experience in this, and this is much easier than the Crimean bridge issue.”

Moscow’s planned railroad is meant to connect Russia’s port city of Rostov-on-Don and Crimea – its key logistical hub in southern Ukraine – as an alternative to the Kerch Bridge, which has come under frequent attack from Kyiv’s drones.

The track runs through key territories in occupied Ukraine including Donetsk, Mariupol and Berdyansk.

Vladimir Putin, the Russian president, announced at a rally after his victory in last month’s sham elections that a crucial segment of the railway was complete.

“I have just been informed that the railway from [Russian] Rostov-on-Don to Donetsk, Mariupol and Berdyansk has been rebuilt,” he said. “We will continue this work, and soon trains will ride all the way to Crimea, and this will be another alternative route, in addition to the Crimean bridge.”

Russia seized tracts of southern and eastern Ukraine in the first months of the 2022 invasion, creating a “land bridge” to Crimea.

Ukraine has attacked and severely damaged the Kerch bridge twice since the invasion, with road and rail traffic across the bridge frequently disrupted by the threat of further strikes.

Andriy Yusov, a Ukrainian military intelligence spokesman, said last month that Moscow is “trying to strengthen the railroad connection” because of frequent Ukrainian attacks on the Crimean bridge, adding that it is Kyiv’s “mission” to prevent Russia from completing the railway’s construction.

“[Russians] are not satisfied with what is happening with the Crimean bridge,” Mr Yusov said. “Therefore, they are trying to strengthen the railroad connection.”