Nigeria ? Eight foreign workers, including one American, were kidnapped from a drilling rig off Nigeria’s oil-rich southern delta Friday in the latest incident highlighting the tenuous security of oil operations in Africa’s largest crude producer.

The kidnappers have offered to negotiate the release of the hostages – six Britons, the American and a Canadian – taken before dawn from the drilling rig Bulford Dolphin, according to the company that operates the rig.

Oil prices jumped by more than $2 a barrel Friday after the report revived concerns about the stability of Nigerian supplies.

Analysts said anxiety about Iran’s nuclear ambitions also supported crude futures.

Police spokesman Haz Iwendi said in the capital, Abuja, that no group had claimed responsibility and no demands had been made.

“Security agencies are trailing them to secure the release of the hostages as soon as possible,” Iwendi said.