The United States told the United Nations Security Council on Wednesday there needs to be greater international pressure on Russia to abide by a ceasefire in Ukraine, as Russia denied it was a threat to its neighbour.

The 15-member council held its 26th meeting on Ukraine. A ceasefire agreed by pro-Russian rebels and Ukraine on September 5 in the Belarussian capital of Minsk is now all but dead and Western fears of a return to all-out conflict are growing.

Ukraine said on Wednesday it was redeploying troops in the east because of fears separatists will launch a new military offensive, despite Russia's denials it sent troops to reinforce the rebels.

"What we need to do is keep ratcheting up the pressure on Russia until it abides by Minsk and chooses the path of de-escalation," US Ambassador to the United Nations, Samantha Power, told the Security Council.

The United States and the European Union started imposing economic sanctions on Moscow in response to Russia's seizure of the Crimean peninsula from Ukraine in March, a month after the overthrow of a Moscow-backed president in Kiev after protests.

European Union foreign ministers are due to meet in Brussels on Monday but are unlikely to step up sanctions against Russia, EU diplomats said on Wednesday.

NATO's top military commander Philip Breedlove said in Bulgaria that the alliance had spotted military equipment arriving from Russia in regions of east Ukraine held by pro-Russian separatist rebels.

Russia's Deputy UN Ambassador Alexander Pankin told the Security Council that NATO's assessment did not reflect the situation on the ground and was an "empty statement and the usual propagandistic falsifications".

In comments directed at Ukraine UN Ambassador Yuriy Sergeyev, he said: "The equipment and forces that the Russian armed forces have are on the territory of my country and they're not threatening yours, they are not moving from my country."

Russia on Tuesday abstained from a Security Council vote to renew authorisation for an EU military operation in Bosnia because it said the mission could be viewed as a bid to accelerate the country's integration into the EU and NATO. Moscow previously voted in favour of the EU operation.

A senior council diplomat, speaking on condition of anonymity, said this was the first example of a spillover of the disagreements over Ukraine into other council issues.

(Reuters)