Hackers have breached the world's largest financial messaging system, used to move billions of dollars a day, months after an multi-million dollar heist at the Bangladesh central bank, US media reported.

The attack against SWIFT -- the Society for Worldwide Interbank Financial Telecommunication -- shows evidence of a wide-ranging attempt to gain access to the system, the network said in a statement due to be released on Friday, the New York Times and Wall Street Journal reported.

SWIFT, which is crucial to the global financial system, was previously believed to be highly secure.

The network, which runs the international messaging system between banks, said the malware attack targeted a commercial bank it declined to name and managed to send SWIFT messages using the bank’s valid codes, media reported.

It follows the theft in February of $81 million from Bangladesh’s account at the Federal Reserve Bank of New York, which was made to move funds to accounts in the Philippines. 

Investigators are still trying to solve the breach. 

In a letter SWIFT is expected to send to its users Friday, it will reportedly say the two attacks shared many similarities and showed the attackers "clearly exhibit a deep and sophisticated knowledge of specific operation controls within the targeted banks".