Kyiv is claiming that in the early hours of Friday morning a Russian armoured column entered Ukrainian territory and was attacked and partly destroyed by Ukrainian forces.

The Russian Defence Ministry denied it and called the claim “some kind of fantasy” but NATO’s Secretary General seemed convinced. Anders Fogh Rasmussen said: “I can confirm that last night we saw a Russian incursion, a crossing of the Ukrainian border. It just confirms the fact that we see a continuous flow of weapons and fighters from Russia into the Eastern Ukraine.”

Kyiv and its Western allies have repeatedly accused Russia of arming separatist rebels in eastern Ukraine, and of sending undercover military units across the border.

If an incursion is confirmed and the government is able to show the remains of Russian military vehicles destroyed on its territory that would bolster Ukranian’s allegations and mark a dramatic worsening of the conflict.

The United Nations said it could not verify the reports from the Ukrainian border but called for an immediate de-escalation.