A number of companies oil sites have been attacked by the Niger Delta Avengers.
Okunbor said unrest in the region had impacted on production, delays to projects and loss of government revenue.
He said: “These illegal acts also have severe environmental consequences. In addition, security threats mean both our development and operating costs are higher than in many other operating environments globally. Ultimately, it means that available funds for the industry don’t stretch as far as they would, if we had a safer operating environment.
“It is clear that security of our assets and people is key to our operations and the federal government has rightly said it will work to ensure a safe and secure working environment for everyone, not just international oil companies”.
The Shell boss said in 2015, theft of crude oil on Shell assets was 25,000 barrels of oil per day, compared with 37,000 bpd in 2014.
The number of sabotage-related spills declined to 93 incidents compared with 139 in 2014.
In 2015, the decrease in theft and spills was also in part due to divestments in the Niger Delta.
He added that both theft and sabotage were still the cause of about 85% of spills from Shell’s pipelines in the region.
Based on survey data compiled by Reuters for the month of May, OPEC crude oil out has fallen by 120,000 barrels per day—a drop largely attributed to the resurgence of Niger Delta militancy.