Operation follows arrest of three alleged leaders of internet activist group Anonymous in Spain on Friday

This article is more than 9 years old

This article is more than 9 years old

The global battle between hacker activists and police intensified Monday with 32 arrests in Turkey and an admission from Spanish police that the group Anonymous had successfully attacked their website in response to arrests made there.

Turkish police arrested 32 suspected local members of Anonymous, including eight minors, according to state news agency Anatolian. The arrests followed a complaint from Turkey's directorate of telecommunications, whose website was taken down on Thursday.

Members of the Anonymous collective said that attack was carried out as a protest against internet censorship by the recently re-elected government of prime minister Recep Tayyip Erdogan, of the moderate Islamist Justice and Development party (AKP).

Turkey is due to introduce an obligatory nationwide internet filtering system in August that will see users forced to sign up to one of four filters.

These are labelled "domestic", "family", "children" or "standard", but hacker activists gathered under the Anonymous umbrella claim they will lead to state control of individual internet use, and allow authorities to keep records of such use.

The police operation in Turkey followed the arrest of three alleged leaders of the so-called Anons in Spain on Friday.

Spanish police admitted that Anonymous had claimed responsibility for blocking their main website briefly in the small hours of Sunday morning in retaliation for the arrests. Police claimed the three detainees jointly formed the "leadership" of Anonymous in Spain. They had allegedly been involved in attacks on the websites of the Sony PlayStation, several banks, an electricity company and the governments of Egypt, Algeria, Libya, Iran, Chile, Colombia and New Zealand.

A server allegedly used in the attacks was taken away when police raided homes in Gijón, Barcelona, Valencia and Almeria. Spanish police said the group had also launched attacks on the Catalan regional police, a trade union and the country's electoral administration.

They said a 31-year-old from Gijón, northern Spain, had been a core member of the leadership. "This person provided infrastructure for the group with a server in their home, from which major international attacks launched by Anonymous were co-ordinated," police said.

But a video posted on YouTube by purported members of Anonymous denied that the three people were leaders.

"The police have lied. They cannot detain our leadership because we have no leadership," they said in a video that featured a "spokesman" wearing the group's Guy Fawkes-inspired mask and peering down from a digital billboard on Madrid's central Gran Vía street. "The server they took did not belong to Anonymous but was a small internet relay chat (IRC) server that we annexed."

The Guy Fawkes masks, which originate from the V for Vendetta graphic novel by Alan Moore and David Lloyd, have become popular among protesters who have gathered in recent weeks in Spanish squares to demand social and political reform.The Anonymous video stated that the group backed the non-violent protest movement, which finished dismantling its tented city in Madrid's Puerta del Sol square in the early hours of Monday morning – ending several weeks of occupation.

A minority of hardcore protesters remain in the Puerta del Sol and in Barcelona's Plaça Catalunya square, while the movement itself concentrates on spreading its popular assemblies to city neighbourhoods and organising one-off protests.

A joint protest in city squares around the globe has been called for 16 June.

Anonymous members cripple websites by overwhelming their servers with traffic in so-called denial of service attacks.

The group says it is not involved in credit-card fraud, but has been held responsible for attacks on the servers of both Mastercard and Amazon.

Spanish police claimed their arrests were the first major action against Anonymous outside the United States and Britain, where several people were detained in January.

The British government has admitted to recent cyber-attacks at the Treasury and, in the words of defence secretary Liam Fox, to a "sustained attack" on the Ministry of Defence.