Urban Angehrn will step down at the end of September 2023, FINMA said in a statement on Wednesday.

Deputy CEO, Birgit Rutishauser, will act as CEO ad interim with effect from Oct. 1, it added.

"The Board of Directors very much regrets this decision and would like to thank Urban Angehrn for his lasting contribution to FINMA during an exceptionally challenging period," the organisation said in a statement.

The regulator has come under fire for failing to act sooner or more effectively to halt the string of scandals at Credit Suisse in recent years.

Switzerland's second biggest lender was brought to the brink of collapse in March when rattled savers withdrew billions in cash, triggering a liquidity crisis.

The stricken bank was eventually bought by cross-town rival UBS in a state-engineered 3 billion Swiss franc ($3.37 billion) rescue.

The Credit Suisse case has triggered scores of legal cases from disgruntled investors who lost money when certain bonds were wiped out or unhappy with exchange ratio for their stock.

($1 = 0.8900 Swiss francs)

(Reporting by John Revill, Editing by Friederike Heine)