Brent crude advanced to a two-week high as tensions escalated between Ukraine and Russia, the world’s biggest energy exporter. West Texas Intermediate moved between gains and losses.

Futures rose as much as 1 percent in London. Russia called for an emergency meeting of the United Nations Security Council after Ukrainian security forces clashed with pro-Russian gunmen in the eastern town of Slovyansk. European officials weighed expanding sanctions against Russia over Ukraine, where they say the government in Moscow is stoking deadly separatist unrest with the same methods it used to destabilize and annex Crimea.

“The situation in Ukraine deteriorated significantly over the weekend, which explains the strength in Brent,” said Bob Yawger, director of the futures division at Mizuho Securities USA Inc. in New York. “The upsurge in unrest justifies trading at these levels.”

Brent for May settlement increased 71 cents, or 0.7 percent, to $108.04 a barrel on the London-based ICE Futures Europe exchange at 10:32 a.m. in New York. It earlier touched $108.38, the highest intraday level since March 28. The volume of all futures traded was 23 percent above the 100-day average.

WTI for May delivery gained 13 cents to $103.87 a barrel on the New York Mercantile Exchange. Volume was 73 percent above the 100-day average.