New York's main contract West Texas Intermediate (WTI) for May delivery eased 12 cents to $102.44 a barrel in mid-morning trade while Brent North Sea crude for May was up five cents to $107.72.

WTI surged $2.12 in New York to its highest level in a month after pro-Russian protesters seized buildings in the eastern Ukrainian city of Donetsk. Brent jumped $1.85 in London.

Analysts said oil prices remained propped up by the heightened tensions in Eastern Europe.

"Investors should be wary and any escalation in tensions could throw global markets off tangent," said Tang Hsin Jin, premium client manager at CMC Markets in Singapore.

The United States on Tuesday accused Russia of sending its agents to stoke the flaring secession crisis in eastern Ukraine that Moscow itself has conceded could spill over into a civil war.

Since Moscow took control of Ukraine's Crimea peninsula last month, several mainly Russian-speaking eastern regions in the ex-Soviet state have seen calls for similar votes by pro-Kremlin groups.

With Ukraine a key conduit for Russian gas to Europe, traders fear that any armed conflict will disrupt supplies and send oil and gas prices skyrocketing.

Russian deliveries account for 34 percent of the natural gas supplies to the European Union, according to the Soufan Group, a US-based intelligence firm.

Dealers are also awaiting the latest US crude stockpiles data out later Wednesday for clues about demand in the world's top oil consumer.

Analysts expect the report to show that crude oil inventories rose by one million barrels, on average, in the week ended April 4, according to a Wall Street Journal survey.

Singapore's United Overseas Bank said markets will also be focused on the release of minutes from the first US Federal Reserve policy-meeting with new chairman Janet Yellen at the helm for further clues on the US economy.