Russia’s army is massing troops and hundreds of pieces of weaponry including mobile rocket launchers, tanks and artillery at a makeshift base near the border with Ukraine, according to a Reuters reporter yesterday.

Many of the vehicles have number plates and identifying marks removed while many of the servicemen had taken insignia off their fatigues. As such, they match the appearance of some of the forces spotted in eastern Ukraine, which Kiev and its Western allies allege are covert Russian detachments.

The scene at the base on the Kuzminsky firing range, around 50 kilometres from the border, offers some of the clearest evidence to date of what appeared to be a concerted Russian military build-up in the area.

Earlier this month, Nato military commander General Philip Breedlove said he believed the separatists were taking advantage of a ceasefire that came into force in February to re-arm and prepare for a new offensive.

Russia denies that its military is involved in the conflict in Ukraine’s east, where Moscow-backed separatists have been fighting forces loyal to the pro-Western government in Kiev.

Russia’s Defence Ministry said it had no immediate comment about the build-up.

The weapons being delivered there included Uragan multiple rocket launchers, tanks and self-propelled howitzers – all weapon types that have been used in the conflict in eastern Ukraine between Kiev’s forces and separatists.

The amount of military hardware at the base was about three times greater than in March this year. At that time, only a few dozen pieces of equipment were in view. Over the course of fours days starting on Saturday, Reuters saw four goods trains with military vehicles and troops arriving at a rail station in the Rostov region of southern Russia, with at least two trainloads travelling on by road to the base

A large section of dirt road leading across the steppe from the Kuzminsky range to the Ukrainian border had been freshly repaired, making it more passable for heavy vehicles.

The road leads to a quiet border crossing typically only used by local residents. On the other side is Ukraine’s Luhansk region, which is controlled by separatists and has been the scene of intense fighting.

Many of the servicemen had taken insignia off their fatigues

Valentina Melnikova, a human rights campaigner who works with families of Russian servicemen, said she had information that Rostov region was being used as a staging post for troops on their way to Ukraine. She said the information came from the mother of a serviceman stationed in Totskoye, near Russia’s border with Kazakhstan. Melnikova said the serviceman heard from commanders that “they are going to be transferred to Rostov region after May 20 and then to Ukraine. They signed papers about non-disclosure of information and about acting voluntarily.

“Of course it was an order. How could it be voluntarily? They are servicemen,” said Melnikova of the Moscow-based Alliance of Soldiers’ Mothers Committees. Her account could not be independently verified by Reuters. In some cases where Russian citizens have been captured in Ukraine by Kiev forces, Russian officials have said they were there of their own accord.

More military hardware trundles into the Matveev Kurgan railway station on goods trains every day. A train that pulled in on Tuesday was carrying 16 T-72 tanks, and military trucks. Over four days, trains delivered at least 26 tanks, about 30 Uragan launchers, dozens of trucks and several armoured personnel carriers and self-propelled howitzers.