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* Basel says to consult on more curbs on banks' internalmodels
* Regulators say reforms won't bump up capital requirements
* Details of trading book review to be published this week
* ECB's Draghi: agreements give banks a clear, post crisispath (Recasts with more detail)
By Huw Jones
LONDON, Jan 11 (Reuters) - The world's top 30 banks face ahigher minimum requirement for their broadest measure ofcapital, global regulators said on Monday as they flagged atwo-tier leverage ratio regime for the first time.
The leverage ratio refers to the amount of capital to abank's non-risk weighted assets, and was set at a preliminarylevel of 3 percent in the aftermath of the 2007-09 financialcrisis.
It is meant to act as a "backstop" to a bank's core capitalratios which are based on the riskiness of assets.
The Group of Central Bank Governors and Heads of Supervision(GHOS) said it agreed on Sunday that the permanent level shouldremain at 3 percent for the bulk of lenders across the world inan announcement that will give the sector much welcomed clarity.
GHOS, however, said it discussed "additional requirements"for the world's 30 "globally systemic banks" which includeGoldman Sachs, HSBC, Deutsche Bank and BNP Paribas.
"The GHOS will finalise the calibration in 2016 to allowsufficient time for the leverage ratio to be implemented... by 1January 2018," it said in a statement.
The regulators have yet to decide what form the extrarequirements should take, such as a flat surcharge or agraduated increase, depending on how big a bank is.
The United States, Switzerland and Britain already expecttheir biggest banks to have a leverage ratio of 4 to 6 percent,well above the current Basel minimum.
GHOS also signed off on new rules from 2019 that will makeit harder for banks to exploit different capital requirementsfor their main banking and trading arms.
It said it would publish the package, known as thefundamental review of the trading book, later this week. It isexpected to scale back capital charges from what was originallyproposed after banks said they would make trading uneconomic.
CLEAR PATH
Banks have long called for clarity on the final shape ofregulation so they can decide on which lines of business theywant to stay in.
GHOS Chairman and European Central Bank President MarioDraghi said the agreements reached on Sunday provide a "clearpath" for completing banking regulation after the financialcrisis.
The trading book review, as the new package is called, takesa more rigorous approach to supervising the so-called internalmodels that big banks use to work out how much capital theyshould hold in case swaps turn sour.
Most lenders calculate capital using standard rules from theregulators, but big banks use their own models, which typicallysave on the amount of capital required.
But regulators have noted wide differences in how muchcapital is held by different lenders to cover essentiallysimilar portfolios and the new rules will help correct this.
The Basel Committee of banking supervisors, which GHOSoversees, will assess the theoretical impact of the new rulesthis year ahead of implementation in 2019.
"As a result of this assessment, the committee will focus onnot significantly increasing overall capital requirements," itadded.
Banks accused regulators of introducing "Basel IV" with thetrading book review, meaning a step change in capitalrequirements from Basel III, the world's core regulatoryresponse to the financial crisis.
Bank of England Governor Mark Carney has repeatedlydismissed talk of a Basel IV in the making.
GHOS also agreed that Basel will launch two publicconsultations this year on further work, including on stoppingthe use of internal models for assessing operational risks.
The second consultation will consider extra curbs oninternal model use for credit risk, such as by using capital"floors", the statement said. (Reporting by Huw Jones; editing by David Clarke)
