The United States, Germany and Britain all indicated they would seek further sanctions against Russia after separatists in Ukraine held on to control of several towns and on Friday detained a bus carrying international observers.
Russia meanwhile warned Kiev it would face justice for a "bloody crime'' in eastern Ukraine, where government forces killed five separatists, and told Germany violence by Ukraine's army and "armed radical nationalists'' must cease.
Chancellor Angela Merkel of Germany, one of the closest European allies of Russia, said she saw no support of a peace accord agreed to last week from Moscow and so must consider more sanctions, a view later repeated by Britain.
In the U.S. market the supply-demand picture is bearish, with inventories in the country climbing to their highest levels on record as production of oil continues to soar and has no outlet out of the country via exports, which are banned. News from Libya was supportive for Brent, with reports its oil ports may stay shut longer than expected.
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