By Huw Jones
LONDON (Reuters) - New rules need to be better tested by regulators for any impact on lending and markets, a banking lobby said ahead of a meeting next month to finalize the latest wave of reforms aimed at preventing another financial crisis.
The Global Financial Markets Association (GFMA) said it has written to the watchdogs, requesting an end to duplication and conflicts in rules already rolled out, and for them to study how the demands will mesh with reforms in the pipeline.
During the 2007-09 crisis, leaders of the Group of 20 economies (G20) called for higher levels of bank capital, a step the Basel Committee of regulators implemented with "Basel III".
Balance sheets have since shrunk as banks shed risky assets, the GFMA said in a statement.
"While in many cases changes to the business models of banks and the structure of markets were intended, in other areas it is likely that the cumulative impacts go beyond those anticipated and may negatively affect the functioning of the financial system," it said.
The Basel Committee, which declined to comment, meets next month as it works to an end-of-year deadline for its key remaining reforms. These include stricter parameters for calculating how much capital big banks should hold.
The GFMA, which comprises regional associations like European banking lobby AFME, refers to these reforms as "Basel IV", meaning they represent a step change in capital requirements, a view regulators reject.
A report from Oliver Wyman commissioned by the GMFA, said one potential unintended consequence for Basel's rules may rise from "liquidity" buffers of cash and bonds that banks must be able to draw on alongside their core capital.
"While these rules work to increase stability and ensure liquidity at individual banks, this may happen at the expense of overall market liquidity," the report said.
The impact of other reforms, such as tougher "margin" or collateral requirements should be included, it added. "However, until all these reforms are finalised and fully implemented, the full impact cannot be determined."
The GFMA does not detail any specific rule change it wants.
Basel is already looking at the impact, calibration and coherence of its rules, and has eased some.[nL5N1791UY]
G20 leaders have also agreed that new rules must not lead to a significant rise in capital at banks.
Regulators say industry assessments often assume the harshest capital treatment, and don't fully take into account the benefits of tougher rules in reducing the likelihood of costly crises.
(Reporting by Huw Jones; Editing by Alexander Smith)