People hold placards as they protest against Turkey's Prime Minister Tayyip Erdogan after the government blocked access to Twitter in Ankara, on March 21, 2014

Turkey's government on Saturday defended its internationally condemned ban on Twitter as a "preventive measure" to stop "character assassinations" following a wave of corruption investigation leaks.

"Twitter has been used as a means to carry out systematic character assassinations by circulating illegally acquired recordings, fake and fabricated records of wiretapping," the office of Prime Minister Recep Tayyip Erdogan said in a statement sent to AFP in English.

The statement added that the government has "always valued the Internet and its accompanying opportunities" but drew the line at "the free circulation of the illegally acquired recordings... which aim at hampering national security."

It also claimed international precedents, including Germany's decision to ban a neo-Nazi Twitter account in October.

Turkey blocked access to Twitter on Thursday after Erdogan, whose government is engulfed in a vast corruption scandal, defiantly vowed to "wipe out" the messaging service.

Erdogan has refrained from making a direct reference to the ban since Twitter went dark.

"It is our duty to take necessary measures against elements that threaten our ," he told a boisterous crowd of his party supporters Saturday in an election rally in the capital Ankara.

The , who has been in power since 2003, has also threatened to ban YouTube and Facebook after crucial local elections on March 30, seen as a crucial gauge of how much damage his government has suffered from the corruption leaks and anti-government protests.

The government said the ban was put in place only after Twitter refused to abide by "hundreds of court rulings" since January ordering the removal of content deemed illegal.

Turkey's Prime Minister Recep Tayyip Erdogan addresses members of his ruling AK Party (AKP) during a session at the Turkish parliament in Ankara on February 25, 2014

"It is difficult to comprehend Twitter's indifference, and its biased and prejudiced stance; we believe that this attitude is damaging to (Twitter) and creates an unfair and inaccurate impression of our country," the statement read.

Ankara urged Twitter and other to respect the principle that "whatever is crime in real life is also a crime in cybernet".

New Twitter user, aged 83

Critics see the ban as a desperate attempt by Erdogan to stem the flow of damaging revelations that have engulfed his inner circle since the corruption investigation went public in December.

New leaks have surfaced almost daily. Some of the most damaging have come from two Twitter accounts under the names Haramzadeler ("Sons of Thieves") and Bascalan ("Prime Thief") that appear to have access to a huge trove of secret documents and police wiretaps linked to the probe.

Recordings have allegedly caught Erdogan talking with his son about disguising vast sums of money, as well as interfering in business deals, court cases, media coverage and the sale of prime property in Istanbul.

Erdogan has fiercely rejected the corruption allegations and dismissed most of the recordings as "vile" fakes concocted by political rivals.

Turkey's clampdown on Twitter sparked outrage and defiance worldwide, with the United States on Friday calling it "contrary to Turkey's own expressed desire to be a model of democracy".

A protestor looks at his cell phone screen in Istanbul on March 21, 2014

Kemal Kilicdaroglu, leader of Turkey's opposition Republican People's Party (CHP), told a crowd of supporters that Erdogan had "denigrated us before the world".

"While we are striving for democracy ... he is imposing bans," he said as the crowd chanted calls for the government to resign.

Far from curtailing the use of Twitter, the ban led to a huge surge in tweets, with angered Turks using virtual private networks (VPNs) and changing Domain Name Systems to get round the restrictions.

According to unconfirmed reports, however, the government is trying to block access to lists of alternative DNS numbers.

Twitter has also reminded users they can still get onto the platform through SMS text messaging.

Figures from Brandwatch, a social media monitoring agency, showed tweets in Turkey increased by 138 percent after the ban, compared with the day before.

One user tweeted under the @NejlaKoker handle, "I am happy to be on Twitter ... I've become a Twitter user at the age of 83 in order to penetrate bans".