The head of Organization for Security and Co-operation in Europe (OSCE) said on Sunday (8 February) that separatists in Ukraine seemed constantly supplied with weapons that appeared to be arriving from the western border with Russia.

"We haven't witnessed any delivery of weapons as such, but then what we see is that as weapons get destroyed during the military operations, the separatists' side, they always seem to have new weapons at hand, so these weapons must come from somewhere," secretary general Lamberto Zannier said.

"That's all we can say. We are present in larger numbers on the Ukrainian side and we have never seen weapons from there going into the East, so our conclusion is that they must come from the other side."

Asked whether he meant from Russia, Zannier added: "Obviously that's the Russian border, yes."

The head of OSCE also said large amounts of weaponry were present in the region, whose ongoing conflict has been the subject of intense debate at last weekend's Munich Security Conference.

"Well, there are multiple rocket launchers and there are heavy artillery including howitzers, heavy howitzers on tracks and tanks, of course, and various artillery systems of many calibres. They seem to have plenty of ammunition, so the conflict is really continuing and the availability of weapons and ammunition and fuel doesn't seem to be a problem," he said.

"We have a border monitoring operation, all the Russian territory, we are covering two border crossing points, but that's a very limited operation because those are two points out of a total of eight that are not controlled by the Ukrainian border services on the other side, and we are not patrolling the green border between these crossing points, so we don't have a full picture of whether there are illegal crossings on that border."

The EU's foreign policy chief said on Sunday she did not expect any transatlantic rift with Washington over Ukraine if the US went ahead with proposals to supply arms to Kiev.

With pro-Russian separatists making gains in eastern Ukraine, discussions are under way in Washington about whether the US should send weapons to the Ukrainian army.

"The issue of the military equipment is a sensitive one. Of course the Ukrainian military also needs support, but there is also a risk of, how can I say? Providing a new, how can I say, narrative to the conflict, internationalising the conflict more," said Zannier.

"And we've already heard on the separatist's side, on the Russian side, sometimes, lines saying: 'This is the war against the West, this is a war against Nato.' And this line will become more robust, may even lead down the line to more direct intervention of Russia in this conflict, which is not what we want to see at all."

A number of European ministers at last weekend's Munich Security Conference opposed sending weapons, fearing it could further escalate the conflict.