FRANKFURT, March 20 (Reuters) - European supervisors tried to stop a rout in the market for convertible bank bonds on Monday, saying owners of this type of debt would only suffer losses after shareholders have been wiped out - unlike what happened at Credit Suisse (CSGN.S). Regulators in the European Union and Britain were reacting to a decisions by Swiss authorities to write off Credit Suisse's Additional Tier 1 (AT1) bonds even as stockholders received shares in UBS (UBSG.S). The EU regulators - the European Central Bank, the European Banking Authority and the Single Resolution Board - said they would continue to impose losses on shareholders before bondholders. The comments helped the price of bank bonds cut losses and were echoed by the Bank of England shortly after. Credit Suisse's AT1 bonds contained a clause allowing Swiss authorities to write them off if the bank became unviable, regardless of what happens to the shares.

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