Britain's biggest banks will be asked to pay more towards the cost of regulating the financial sector under the government's new so-called "twin peaks" system of supervision, Sky News reported Monday.The Financial Conduct Authority (FCA) and Prudential Regulation Authority (PRA), which took over responsibility for City regulation last week, are expected to announce a 20% increase in fees of £600m to major banks, brokers and insurers. The UK's largest lenders including Barclays and the Royal Bank of Scotland will be hit the most with charges of tens of millions of pounds annually, according to insiders. "The PRA's remit is to focus on the major risks within the financial system, and the biggest banks are at the centre of that focus," a source told the news provider.The Financial Services Authority, the predecessor body to the FCA and PRA, last year received £489.1m from the financial industry.Big banks paid on average between £20m and £30m each. They will be expected to pay in the region of 25% more with the new regime.An increase was expected but the extent to which big banks would be charged was unclear. Under the "twin peaks" system the PRA will supervise 1,700 banks, insurers and large investment firms. The FSA will supervise the behaviour at the same firms and have sole responsibility for 25,000 more, most of them brokers, investment advisers and money managers. RD