Royal Dutch oil company, Shell PLC has released its annual Sustainability report for 2011 where it claimed that oil spills at its facilities in Nigeria soared last year.

According to the report released on Thursday, the number of operational spills onshore Nigeria increased to 63 in 2011, from 32 in 2010.

The volume of operational spills also jumped to 5,300 tonnes from 700 tonnes in 2010, largely due to a leak at its offshore Bonga facility.

Shell believes that the higher number of spills resulted from more pipelines being put back into operation, after an improvement in the security situation allowed teams to access facilities.

The oil giant claims that spills resulting from sabotage or attempts to steal fuel from pipelines caused 118,000 tonnes to seep into the environment.

Shell’s report comes as the company faces a lawsuit in London from Nigerians whose communities in the Nigeria’s major oil producing region are affected by oil.