HSBC said a cyber attack temporarily shut down its Internet banking on Friday, the second time the bank's online services have been disrupted in the U.K. this month.
The so-called denial of service attack, which aims to cripple an online system by flooding it with traffic, was "successfully defended," the bank said in an e-mailed statement. Customers had taken to Twitter, saying they were unable to access their personal and business accounts on the final business day of the month, when British salaries are typically paid.
"We are working hard to restore services and normal service is now being resumed," the London-based lender said. "We apologise for any inconvenience this incident may have caused."
British banks have been hurt by a string of outages, some attributed to obsolete software and others to malicious activity by hackers, prompting lawmakers to call for more spending on technology and closer supervision of computer systems by board members.
Earlier this month, HSBC's personal and business customers were unable to access their online or mobile banking services for three days, following a computer glitch in August that left 275,000 business payments delayed. A payments outage at RBS in June affected 600,000 credit and direct-debit transactions, only seven months after the regulator fined the bank 56 million pounds ($80 million) over previous computer failures.