(ShareCast News) - Three major UK insurers said they had received approval to use their internal models to comply with the new European-wide Solvency II requirements to protect against financial shocks.RSA, Prudential and Legal & General are among 19 companies to get full or partial approval for their plans from the UK's Prudential Regulation Authority.FTSE-250-listed Just Retirement and Phoenix Holdings will also use full internal models.The new rules come into force on 1 January 2016. Firms must prove they have enough capital to survive a one-in-200-year financial shock, and still pay out pensions and policies.However, bank of England Governor Mark Carney on Monday criticised the rules around Solvency II. Appearing before a European Parliament committee in his role as vice-chair of the European Systemic Risk Board, Carney said the rules for insurers needed reform."In my view, more can be done to ensure that Solvency II creates the right framework for long-term investment," Carney said. A replacement for the Solvency I rules was formally created in an EU directive in 2009. Many UK firms have complained about the high costs of implementing the directive and the ongoing expenditure of running compliance systems.