Twitter ban: Turkey's President Gul challenges PM's move
President Abdullah Gul has challenged a ban on Twitter in Turkey after Prime Minister Recep Tayyip Erdogan vowed to "wipe out" the micro-blogging service.
Twitter users across the country reported that the site had been blocked on Thursday.
But like many others, President Gul evaded the ban to tweet that the "shutdown was unacceptable."
Mr Erdogan is angry that people used Twitter to spread allegations of corruption in his inner circle.
"I don't care what the international community says at all. Everyone will see the power of the Turkish Republic," Mr Erdogan said in a speech on Thursday.
'Not technically possible'
President Gul took to the site on Friday to say that websites should only be blocked if courts found they had violated personal privacy.
He said it was not "technically possible to totally block access to platforms used all over the world" and added that he hoped the decision would "not last long."
Like Mr Erdogan, Mr Gul is a member of the Islamist-rooted Justice and Development Party (AKP).
In Turkey, the government holds most power but the president can veto laws, appoint officials, and name judges.
The European Union said it was worried about the move to block Twitter, with Stefan Fuele, the EU commissioner for enlargement, saying he was "gravely concerned" by Prime Minister Erdogan's policy on free speech.
European Commission Vice President Neelie Kroes described the blocking of the site as "groundless, pointless, cowardly."
Turkey's lawyers' association asked a court to overturn the ban, arguing it was unconstitutional and violated Turkish and European human rights laws. Turkey's main opposition party also said it would try to have the decision reversed.
Those Twitter users who managed to circumvent the ban took to the service to voice anger at the move.
One user tweeting under the name @MuratYetkin2 said: "I see that everyone is here. Looks like the ban has been circumvented in less than 12 hours."
Mr Erdogan took action against Twitter after some users had posted documents reportedly showing evidence of corruption relating to his office - a claim he denies.
His spokesman said Mr Erdogan had been forced to act after the social media company had failed to respond to a court ruling in Turkey to remove some links.
Some users trying to open twitter.com were redirected to a statement by Turkey's telecommunications regulator citing a court order to apply "protection measures" on the website.
Twitter has so far made no public comment on the court order but a spokesman said it was looking into the outage. Twitter also posted a message in both English and Turkish telling users how to send tweets via text messages.
There are about 10 million Twitter users across Turkey.
In 2010, the country lifted its ban on YouTube - two years after it blocked access to the website because of videos deemed insulting to the country's founder, Mustafa Kemal Ataturk.