Crude oil continued to rise above $ 55 a barrel on Monday, supported by a new closure of Libya's largest fields and heightened tension over Syria after the US missile attack.
A Libyan oil source said the spark field was closed on Sunday after it disrupted a pipeline group linking it to the oil refinery. Work resumed in the field in early April after a week-long break.
"The sudden and repeated halt in production is still a source of support for oil prices," said Carsten Frech of Commerzbank.
London Brent crude rose 42 cents to $ 55.66 a barrel by 0840 GMT, while US crude was up 33 cents at $ 52.57 a barrel.
Oil has also risen as tensions mount in the Middle East, which pumps more than a quarter of world oil production. Crude rose last week after the United States fired rockets at an air base of the Syrian government.
The spark field was closed for a week until April 2. OPEC member Libya has pumped a tiny share of its production capacity because of conflict and unrest a year ago