Hackers tried to steal 55 million roubles ($940,000) from Russian state bank Globex using the SWIFT international payments messaging system, the bank said on Thursday, the latest in a string of attempted cyber heists that use fraudulent wire-transfer requests.

Globex President Valery Ovsyannikov told Reuters via the press service that the attempted attack occurred last week, but that “customer funds have not been affected.”

The bank’s disclosure comes after SWIFT, whose messaging system is used to transfer trillions of dollars each day, warned late last month that the threat of digital heists is on the rise as hackers use increasingly sophisticated tools and techniques to launch new attacks.

SWIFT said in late November that hackers continued to target the SWIFT bank messaging system, though security controls instituted after last year's $81 million heist at Bangladesh's central bank have helped thwart many of those attempts,

Sources familiar with last week's attack on Globex said the bank had spotted the attack and been able to prevent the cyber criminals from stealing all the funds they had sought, according to a report in the Kommersant daily. The hackers only withdrew around $100,000, the report said.

Globex is a part of the state development bank VEB. VEB plans to transfer Globex to the state property management agency, sources familiar with the talks told Reuters this week.

SWIFT representatives declined to discuss the Globex case.

“We take cyber security very seriously, and we investigate all threats very seriously, taking all appropriate actions to mitigate any risks and protect our services," the group said in a statement emailed to Reuters. "There is no evidence to suggest that there has been any unauthorised access to SWIFT’s network or messaging services."

Brussels-based SWIFT has issued a string of warnings urging banks to bolster security in the wake of the February 2016 cyber heist at Bangladesh bank, which targeted central bank computers used to move funds through the messaging system.

While SWIFT has declined to disclose the number of attacks or identify any victims, details on some cases have become public, including attacks on Taiwan's Far Eastern International Bank and Nepal's NIC Asia Bank.

Shane Shook, a cyber expert who has helped investigate some hacks targeting the SWIFT messaging network, said that at least seven distinct groups have been launching such attacks for at least five years, though most go unreported.