New York's main contract, light sweet crude for April delivery, rose from $1.00 to $99.10 per barrel after passing the $100 mark for the first time since October 2008 on Wednesday.

Brent North Sea crude for delivery in April was up 85 cents to $112.10.

Fears of unrest spreading throughout the region from embattled Libya was pushing crude prices up, said Victor Shum, senior principal of Purvin and Gertz energy consultants in Singapore.

"The concerns go beyond Libya, which is a relatively small oil producer, to the bigger oil producers that may be affected if the revolt spread," he told AFP.

Libyan leader Moamer Kadhafi's pledge Wednesday to crush anti-regime protesters for control over the country also added fuel to the fire, Shum added.

Libya has Africa's largest oil reserves and is the continent's fourth largest producer and is a member of the Organisation of the Petroleum Exporting Countries (OPEC), the cartel that produces about 40 percent of global supplies.

Kadhafi's son Saadi said his father would be a key member of any new regime after the "positive earthquake" rocking Libya and acknowledged the need for "new blood", the Financial Times reported Thursday.

Unrest also rocked Libya, Bahrain and Yemen.