The Metropolitan Police has confirmed that five men have been arrested in connection with conducting distributed denial-of-service attacks (DDoS) at the end of last year.

The Met's Police Central e-Crime Unit (PCeU) arrested five males aged, 15, 16, 19, 20 and 26 from residential addresses in the West Midlands, Northants, Herts, Surrey and London this morning under the Computer Misuse Act 1990.

A statement said: “They are part of an ongoing MPS investigation into Anonymous which began last year following criminal allegations of DDoS attacks by the group against several companies. This investigation is being carried out in conjunction with international law enforcement agencies in Europe and the US.”

Talking to SC Magazine, Luis Corrons, technical director at PandaLabs, said that he felt more people could be tracked and ultimately arrested as the tool that was used; the LOIC (Low Orbit Ion Cannon) does not hide a user's IP address.

He said: “Using it puts your IP address on display and companies can look at their log files and work with law enforcement that will arrest people. In 2011, we will see more cyber protests and all governments, not just those who are non-democratic, will be concerned about the level of action.

“They may arrest 200 people, but these arrests may be a warning. There are different consequences and people are not aware of the implications.”

A statement by the pro-internet freedom Pirate Party said that it accepted that while it is important that both justice is done and seen to be done against those who break the law, care should be taken to ensure that no individuals are ‘made an example of', nor blamed for the actions of many hundreds or thousands of activists.

Loz Kaye, leader of Pirate Party UK, said: "These arrests and comments by ACPO threatening 'more extreme tactics' to deal with hacktivists represent a worrying ratcheting up of confrontation. Many in the online community frankly feel under siege. It is time for engagement from mainstream politicians, or otherwise radicalisation can only increase."

Graham Cluley, senior technology consultant at Sophos, said: “Clearly the authorities are not looking sympathetically on those they believe are assisting the denial-of-service attacks and that's not just true in the UK.

“Clearly computer users should think very carefully before being recruited as a hacktivist to launch attacks on websites belonging to other people, otherwise it could be that the police are knocking on your door next.”