Related content

The hacking group announced details of the security breach on its website, including links to HSBC's US and UK sites.

In a shock strike, the so-called security firm took the major bank's UK and US servers offline on Tuesday.

In a statement, the cyber attackers wrote: "Hello Guys, today we checked HSBC Bank security, and their website was able to be attacked!, and now we took it down.

"If you are working on HSBC Bank, please contact us…we will stop the attack and we will let you know how to protect it from people attacks!”

Related content

TARGETED: OurMine claims it can 'help you with your accounts security'

Both HSBC websites were back online by early Wednesday, Vocativ reported.

In a second post on Tuesday, the group announced it "stopped the attack” after "a staff of HSBC talked with us".

It is not know whether the hack caused any disruption for HSBC's online customers.

Daily Star Online has contacted HSBC for comment.

SECURITY BREACH: The group announced it 'stopped the attack' after talking to the bank

OurMine says it is an account and company security firm on its website.

The company claims it can "help you with your accounts security" and "scan your website to find vulnerability and how to fix it".

The cyber strike on HSBC comes after reports the firm targeted the social media accounts of prominent CEOs to boost its reputation.

Its most high profile attack came in June, when it claimed to have hijacked Facebook boss Mark Zuckerberg's social media accounts.

Google"s Sundar Pichai, Uber"s Travis Kalanick, and Twitter"s Jack Dorsey are also reportedly among its victims.