Crude prices jumped more than 2% to a new eight-month high today amid a surge in trading activity concentrated in the ICE Brent futures contract.

While improving risk appetite and fresh attacks on crude facilities in Opec producer Nigeria provided some fundamental support, numerous traders in Asia were at a loss to explain why volumes had surged by 10 times their norms, sending prices spiking.

US crude for August delivery rose to a new eight-month high of $73.38 a barrel, but later cooled to trade at $72.09, up $1.60 on the day.

London Brent, where trading volume in the front month contract surged to more than 12,000 lots versus the less than 1000 lots that normally trade in Asia hours, led the rally, gaining $1.93 a barrel to $72.92.

While traders said that the main catalyst for the move appeared to be Brent, not US crude, the trigger was difficult to pinpoint.

"This could be end of quarter movement, and traders are trying to push prices higher and then selling before closing their books," said Mark Pervan of ANZ Bank. "Haven't seen any new catalyst on the news front."

Driven by hopes of a global economic recovery, oil prices are on track to post a near 50% jump in the second quarter, the highest quarterly percentage gain since 1990.

"The equities markets are having a strong performance, so risk appetite is increasing and that is pushing oil prices higher. Violence in Nigeria is also supportive," said Victor Say, an analyst at Informa Global Markets in Singapore, reported Reuters.