Royal Dutch Shell says it is losing the equivalent of 30,000 barrels of crude oil per day because of recent attacks against its installations in Nigeria.

The unrest in Nigeria, Africa's biggest oil producer, helped drive oil prices to a record high above 126 dollars on Friday.

Anglo-Dutch oil group Shell, Nigeria's largest oil operator, accounts for around half of the country's 2.1 million barrels per day output.

An upsurge in attacks on its facilities has forced it to cut back on production.

Niger Delta militant groups have sabotaged several supply pipelines owned by Shell and other oil operators in the restive region.

Overall, violence in the Niger Delta has reduced Nigeria's total production by a quarter in the past two years.