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.