SWIFT, the global financial messaging system, on Tuesday disclosed new hacking attacks on its members¡¯ banks as it pressured them to comply with security procedures instituted after February¡¯s high-profile $81 million heist at Bangladesh Bank.

In a private letter to clients, SWIFT said new cybertheft attempts ¡ª some of them successful ¡ª have surfaced since June, when it last updated customers on a string of attacks discovered after the attack on the Bangladesh central bank.

¡°Customers¡¯ environments have been compromised, and subsequent attempts made to send fraudulent payment instructions,¡± according to a copy of the letter. ¡°The threat is persistent, adaptive and sophisticated ¡ª and it is here to stay.¡±