|Anonymous backed the revolutions in Tunisia and Egypt [Image courtesy of Anonymous]
A string of Turkish government websites have been compromised by members of Anonymous, the international cyber activist group, as part of a protest against alleged internet censorship in the country, authorities have said.
Access to Turkey's telecoms authority website, identified as a main target in the group's "Operation Turkey" campaign against a planned new online filtering system, was blocked as planned at 1500GMT on Thursday.
While authorities worked to limit the disruption, other sites were also blocked including those related to social security, meteorology and several telecoms-related sites. One of these was the official site where people can report inappropriate internet content.
"We will not stand back in the face of an attack on our country by this group. We call on the state bodies responsible for fighting such crimes to act," Yavuz Kocoglu, head of an association set up to tackle IT crimes, said in a statement.
In a posting on its official website, Anonymous issued a statement pledging to fight what it said was internet censorship there.
The new filtering system, due to be implemented on August 22, mandates that all online users must sign up for one of four filters - domestic, family, children or standard.
The 'hactivist' group said the filtering system would make it possible to keep records of people's internet activity.
"Though it remains opaque why and how the system will be put in place, it is clear that the government is taking censorship to the next level," the statement said.
"We will bring our support to circumvent censorship and retaliate against organisations imposing censorship."
The hacking of Turkish government sites came after tens of thousands of people demonstrated in Istanbul in May against online censorship and plans for the filtering system.
'Betraying a nation'
But the Information and Communication Technologies Authority says there will be no difference between the standard filter and the current system, but that the other filters would offer the option to restrict access for those who wanted it.
A group of pro-government Turkish hackers said on their website that they had launched a retaliatory strike against Anonymous sites.
"The issue is not censorship, it is betrayal of the nation," the statement said.
Anatolia, the semi-official Turkish news agency, quoted Huzeyfe Onal, a cyber security expert, as saying Anonymous planned to disrupt the electoral authorities system during Sunday's election.
However, Anonymous denied this, saying the poll would not be disrupted.
Anonymous came to prominence since last year with a series of high-profile campaigns, temporarily disrupting MasterCard Inc and Visa Inc sites for blocking payments to WikiLeaks, to compromising Tunisian and Egyptian government sites in solidarity with popular uprisings that ousted the leaders this year.