A group of computer hackers that wants to target Daesh has claimed it was behind a cyber attack on the BBC which it intended as a test of its own capabilities, according to messages sent to a reporter at the broadcaster on Saturday.

"It was only a test, we didn't exactly plan to take it down for multiple hours," the group called New World Hackers said in a message sent to the BBC's technology correspondent, Rory Cellan-Jones, which he posted on Twitter.

"We realize sometimes what we do is not always the right choice, but without cyber hackers ... who is there to fight off online terrorists?"

The BBC's online services, including its news website and iPlayer catch-up TV platform, were taken down for a few hours on Thursday by a large web attack. The broadcaster, citing sources inside the corporation, described as a "distributed denial of service (DDoS)" attack.

A DDoS attack typically targets sites by flooding servers with messages from multiple systems so they are unable to respond to legitimate traffic.

A BBC spokeswoman said the broadcaster would not comment on the claim of responsibility made by the group.