(Reuters) - A new lawsuit by U.S. hedge fund Appaloosa LP accuses the former Credit Suisse of misleading investors about its health before $17 billion of its bonds were written down to zero in a government-orchestrated rescue by Swiss rival UBS.

In a complaint filed on Tuesday in the Newark, New Jersey federal court, Appaloosa said two investors it advised suffered significant losses when their Additional Tier 1 bonds were wiped out in March 2023, just 1-1/2 weeks after they began purchases.

Appaloosa said Credit Suisse Chief Executive Ulrich Koerner falsely proclaimed that liquidity was "very strong" and "getting stronger" though the bank was suffering a deposit run, mirroring a run that led to Silicon Valley Bank's collapse that month.

The lawsuit accuses Credit Suisse, Koerner and former Chairman Axel Lehmann of "lying to the market about Credit Suisse's deteriorating liquidity," and seeks unspecified damages under U.S. securities laws and a New Jersey racketeering law.

UBS declined to comment.

A lawyer for Appaloosa and the investors, Azteca Partners LLC and Palomino Master Ltd, did not immediately respond to a request for comment. The plaintiffs are based in Short Hills, New Jersey. Bloomberg reported the lawsuit on Tuesday.

Additional Tier 1 bonds, or AT1 bonds, are a capital cushion that can support banks during market turmoil.

Though they rank above shares in banks' capital structures, Switzerland's financial regulator FINMA had no obligation to pay holders of Credit Suisse's AT1 bonds.

Its decision to seize the bonds while allowing UBS to buy Credit Suisse for $3 billion shocked investors, and has prompted many lawsuits in the United States and Europe.

UBS raised $3.5 billion in November in its first AT1 bond sale since buying Credit Suisse.

The case is Palomino Master Ltd et al v Credit Suisse Group AG et al, U.S. District Court, District of New Jersey, No. 24-05539.

(Reporting by Jonathan Stempel in New York; Editing by Kirsten Donovan)

By Jonathan Stempel