(38)To ensure the safety of CCPs, a CCP should accept as collateral a commercial bank guarantee only after a thorough assessment of the issuer and of the legal, contractual and operational framework of the guarantee. Unsecured exposures of CCPs to commercial banks should be avoided. Therefore, commercial bank guarantees may be accepted only under strict conditions. Those conditions are generally met in markets characterised by a high concentration of commercial banks willing to provide credit to non-financial clearing members. For this reason a higher concentration limit should be permitted in these cases.