Swift, the network which thousands of banks around the world use to transfer millions in funds daily, has issued a significant malware warning.

According to Reuters, the cooperative of 3,000 financial institutions revealed that it had become aware of "a number of recent cyber attacks" on Monday.

Its client software is being targeted.

The announcement comes after attackers stole $81 million from the central bank of Bangladesh, most likely by hacking into Swift.

Swift spokeswoman Natasha Deterean told Reuters that a software update has now been released to "to assist customers in enhancing their security and to spot inconsistencies in their local database records", while financial institutions have been put on alert to scrutinise their security procedures.

The Bangladesh hackers appear to have manipulated the Alliance Access server software which banks use to interface with Swift's messaging platform to cover up fraudulent transfers.

The 'evtdiag.exe' malware allowed the hackers to change records within Swift databases.

In theory, it could be applied to other financial institutions and in different countries.

Adrian Nish of BAE Systems told Reuters that it was one of the most elaborate hacks he'd ever encountered.

The hackers were detected by Deutsche Bank because they misspelt the word "foundation" as "fandation".