Federal prosecutors in Manhattan on Tuesday charged KuCoin, one of the world's largest cryptocurrency exchanges, with violating U.S. anti-money laundering laws by failing to vet customers, allowing billions of dollars in illicit funds to be transferred since its founding in 2017.

Prosecutors said the Seychelles-based exchange sought business from U.S. customers without registering with the Treasury Department and putting in place procedures to verify clients' identities as required by U.S. law.

KuCoin posted on social media site X that customer assets are safe and its lawyers are looking into the allegations.

"KuCoin respect the laws and regulations of various countries and strictly adheres to compliance standards," it said.

Prosecutors also charged the exchange's founders, Chinese nationals Chun Gan, 34, and Ke Tang, 39, with conspiracy. They remain at large, according to prosecutors.

The U.S. Commodity Futures Trading Commission separately filed a civil lawsuit against KuCoin alleging it failed to register its futures and swaps activities with the regulator.

KuCoin in December agreed to block New York users from its platform and pay $22 million to settle the state's lawsuit accusing it of failing to register there.

KuCoin trails Binance, Coinbase and Kraken among cryptocurrency spot exchanges on factors including traffic, liquidity and trading volumes, according to the data company CoinMarketCap. (Reporting by Jody Godoy in New York; Editing by Andrea Ricci and Costas Pitas)