Private security officials say pirates have hijacked a fuel tanker off the coast of Nigeria's oil-rich southern delta, kidnapping foreign sailors in the region's latest attack.

Security officials said Tuesday that the hijacking of the MT Matrix I happened Saturday off the coast of Bayelsa state. The officials said the pirates kidnapped both Nigerian and Pakistani sailors in the attack.

A military spokesman in the delta referred calls for comment Tuesday to Nigeria's navy. Commodore Kabir Aliyu, a navy spokesman, said there had been no report of a hijacking made to officials.

The Gulf of Guinea, which follows the continent's southward curve from Liberia to Gabon, has seen an escalation in violent pirate attacks. Insurers have listed Nigeria, neighboring Benin and nearby waters in the same risk category as Somalia.