Credit Suisse AG staff are making preparations to sue the Swiss financial regulator over $400 million of bonuses that were cancelled following the bank's rescue by UBS, the Financial Times reported on Monday.

Law firms Quinn Emanuel and Pallas, which are already suing Swiss regulator Finma on behalf of investors who owned AT1 bonds, have received multiple requests from senior managers at Credit Suisse to take legal action on their behalf, the report said. (Reporting by Shivani Tanna in Bengaluru; Editing by Varun H K)