(Adds details, background) LONDON, May 11 (Reuters) - U.S. oil company Chevron <CVX.N> said on Friday it was evacuating hundreds of nonessential personnel from offshore operations in Nigeria due to security concerns. Chevron spokesman Michael Barrett said the evacuation would not further impact the company's production in Nigeria. "We are temporarily suspending some nonessential work activity in offshore operations to ensure the safety and security of our workforce," he said. "The number of personnel impacted is going to be in the hundreds." Militant attacks this month have prompted Chevron to cut production by 42,000 barrels per day at its Escravos oilfields and 15,000 bpd at its Pennington terminal. Chevron said it would regularly review the security situation in Nigeria, but declined to say when the personnel would return. The evacuation will affect some drilling rigs, construction barges and support vessels. A surge in violence in Africa's largest oil producer has led to the shutdown of more than 750,000 bpd, or around 25 percent of the country's production capacity.
