UPDATE 1-Nigeria says unrest keeps it short of OPEC quota

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PORT OF SPAIN, May 11 (Reuters) - Persisting unrest and violence in Nigeria's Niger Delta is preventing the African oil producer from meeting its OPEC output quota, a senior Nigerian oil ministry official said on Monday.

"The problem is with the Niger Delta location. We have not been able to meet OPEC obligations," Femi Olayisade, Permanent Secretary in Nigeria's Ministry of Petroleum Resources, told Reuters on the sidelines of an oil conference in Trinidad and Tobago.

OPEC has set Nigeria an implied production target of 1.67 million barrels per day (bpd) that came into effect on Jan. 1.

Militants in the restive oil-producing Niger Delta have for several years been attacking energy installations there and also often kidnap foreign oil workers.

Olayisade said the Nigerian government had been working "tirelessly" to restore peace to the Delta.

"We are making attempts to bring peace to the Niger Delta and once there is peace, we will meet our quota for OPEC production as soon as possible," he said.

"Without this (peace), our production efforts are seriously curtailed," he added. (Reporting by Linda Hutchinson-Jafar; Editing by Pascal Fletcher and Marguerita Choy)