KIEV - The United States expressed fury at Russia's "lies" over Ukraine after European powers urged a frayed ceasefire be respected, while a rare overnight calm was reported in the war zone on Wednesday.
But the crisis still simmered dangerously. Britain said it was dispatching a team of soldiers to Ukraine for "training" and warned Russia could be cut off from the SWIFT international banking network, while Russia's Gazprom is threatening to stop gas supplies to Ukraine.
The United States has not yet said whether it favours sending US weapons to Kiev, as some officials have been suggesting.
But US Secretary of State John Kerry on Tuesday launched his most scathing accusation to date over Russia's alleged involvement in the conflict.
"They have been persisting in their misrepresentations - lies -- whatever you want to call them - about their activities there to my face, to the face of others, on many different occasions," he told US lawmakers.
He said Russia was also engaging in "a rather remarkable period of the most overt and extensive propaganda exercise that I've seen since the very height of the Cold War".
British Prime Minister David Cameron announced separately that his country was sending up to 75 soldiers to Ukraine on a training mission, with some leaving for Kiev this week. He said they would not be sent to the conflict zone.
Cameron urged the EU to look at wide-ranging sanctions on Russia's economy, which is already toppling into recession because of a drop in oil prices.
"We should look at other avenues as well -- obviously looking at the SWIFT banking issues is a big decision but there is a logic for it," he said.
SWIFT refers to the international financial industry's secure messaging system that facilitates transactions. Western sanctions in 2012 cutting Iran off from the system for defying UN resolutions over its nuclear programme dealt a severe blow to the Islamic republic's economy.
The developments revealed deep Western exasperation with the violence in Ukraine, which is continuing albeit at a lower level since a February 15 ceasefire negotiated in the Belarus capital Minsk came into effect.
The United States and EU nations blame Russia for fomenting the 10-month-old insurgency in east Ukraine, accusing Moscow of sending intelligence officers, troops, tanks and missiles to back it.
Moscow's denials have been dismissed. The United States says it has evidence of Russian military deployments, and pointed to similar denials -- later renounced -- over Russian troop involvement ahead of last year's annexation of Crimea.
Russia has flexed its muscles in return. Its state-owned gas giant Gazprom has threatened to cut off supplies to Ukraine this week, disputing Kiev's claim that the gas needed was paid for. Much of the gas that flows through Ukraine goes on to supply the EU market.
No arms pull-back
A meeting Tuesday in Paris between the foreign ministers of Russia, Ukraine, Germany and France failed to procure any breakthrough. The diplomats simply said they wanted to see the ceasefire fully observed and heavy weapons pulled back from the frontline.
The ceasefire has been broken regularly. The worst violation was last week when the rebels overran Debaltseve, a strategic transport hub located between their strongholds of Donetsk and Lugansk.
Fighting has also been continuing near the port city of Mariupol, which represents one of the main obstacles to the pro-Russian forces creating a land corridor from the Russian border to Crimea.
Ukraine's army and rebels both said on Wednesday that, unusually, no combat was reported overnight.
But there was still no confirmation of any arms withdrawal from the frontline.
Kiev says it will not carry out a pull back until a full and "comprehensive" ceasefire is observed.
On Wednesday, the insurgents took journalists to Obilne, a village 20 kilometres (12 miles) from Donetsk, to witness movements of artillery canon and trucks.
They said it was an arms withdrawal, but there was no way of verifying where the material was going or if it would return.
"We are applying the Minsk accords," a rebel commander known by the nickname "Khorochi" told AFP. "Yesterday (Tuesday), we pulled back Grad rocket launchers and the day before, tanks."
He added: "We are following orders to pull back heavy weapons, but the Ukrainians aren't."
The Organisation for Security and Cooperation (OSCE) in Europe tasked with verifying implementation of the Minsk truce has not confirmed any arms withdrawal.
The head of the OSCE mission in Ukraine, Ertugrul Apakan, said in a statement that the warring sides "still have not provided" information needed to determine what, if any, arms withdrawals have occurred.