Russia’s top oil producer Rosneft has turned to UK-certified lawyers in its fight against Ukraine-related Western sanctions which have hit the company’s output and prospects for its push to tap Arctic riches. “Provider undertakes to render legal services with regard to challenging economic sanctions and to protect interests of the client in general in respect to any other legal matters,” the document said. BP owns a 19.75 percent stake in Rosneft, which due to the sanctions faces limits on its access to capital markets, curbing its ability to fund development work.