A hacking group calling itself FawkesSecurity has claimed responsibility for yesterday’s denial of service attack on banking giant HSBC.

"As some of you may be aware HSBC bank suffered several DDoS attacks on the named sites in the past hours us.hsbc.com hsbc.co.uk hsbc.com hsbc.ca they were all brought down by #FawkesSecurity," the group claimed on text hosting website Pastebin.  

The group’s Twitter account posted "hsbc.co.uk ‘TANGODOWN’" at 10:39 yesterday morning, followed by similar tweets about other HSBC sites. In a YouTube video, the group – which describes its members as ‘ethical hackers and social engineers’ – declined to explain its motives.

HSBC confirmed the attack in a statement yesterday afternoon. "On 18 October 2012 HSBC servers came under a denial of service attack which affected a number of HSBC websites around the world," it said. "This denial of service attack did not affect any customer data, but did prevent customers using HSBC online services, including internet banking."

The bank has since said that as of 3:00 am this morning, "all HSBC websites globally returned to normal activity".

The timing of the group’s Twitter postings lends credence to its claims, but Twitter users claiming to be Anonymous members have falsely claimed responsibility for attacks before.

Last month, a Twitter user called "Anonymous Own3d" said they were responsible for an outage at US hosting website GoDaddy.com. The company later said that the outage was caused by a network fault.

"It was not a "hack" and it was not a denial of service attack (DDoS)," said GoDaddy interim CEO Scott Wagner in a statement.