Hong Kong - Oil prices were mixed on Tuesday after rallying in the previous session in response to a vote in eastern Ukraine to break away from the country, fuelling fears of a civil war in the country.
The US benchmark, West Texas Intermediate for delivery in June, eased 8 cents to $100.51 a barrel, while Brent North Sea crude for June gained 1c to $108.42 a barrel.
Prices jumped on Monday after pro-Russian separatists claimed a victory in weekend referendums in Donetsk and Lugansk and appealed to be annexed by Moscow. The move mirrors events in Crimea in March that saw the peninsula become part of Russia.
Kiev denounced the latest balloting as a "criminal farce", while the United States and European Union called the polls illegal.
Ukraine is a major conduit for Russian oil and gas exports to Europe, and any escalation of the conflict could disrupt supplies and send prices soaring, analysts say.
"The market looks to be supported by optimism over the US equity market rally and geopolitical concerns in Ukraine," said Jonathan Barratt, chief executive officer at Sydney-based Barratt's Bulletin.
"If the US inventory levels show a draw this week it may provide more support to the improving demand picture."
The US Department of Energy will on Wednesday release its stockpiles report for the country, with a fall indicating a pick-up in demand in the world's biggest economy.
Last week it said reserves sank by 1.8 million barrels in the week to May 2, confounding market expectations for a gain of 1.2 million barrels.
However, Barratt said price rises could be capped by concerns over China's economy and increases in supplies from the United States and Libya, where a major terminal has reopened after a months-long shutdown caused by protests.