LONDON - Oil giant Royal Dutch Shell Plc said it was being sued for causing climate change, suggesting recent court set-backs for environmentalists had not put an end to global warming lawsuits.

The Anglo-Dutch group said in its annual report, published on Thursday, that, "Shell, together with other energy companies, has been subject to litigation regarding climate change".

"We believe these lawsuits are without merit and are not material to Shell," the world's second-largest non-government controlled oil company by market value added.

Last year, the US Supreme Court rejected a lawsuit against five big power companies, that sought to force them to cut their carbon dioxide emissions, claiming the utilities had created a public nuisance by contributing to climate change.

Shell gave no further detail on the suits.