Twitter users in Turkey reported widespread outages, hours after Prime Minister Tayyip Erdogan threatened to shut down the social media platform as he battles a damaging corruption scandal.
Some users trying to open the Twitter.com website were taken to a statement apparently from Turkey's telecommunications regulator.
The statement cited four court orders as the basis for blocking the site, where some users in recent weeks have posted voice recordings and documents purportedly showing evidence of corruption among Mr Erdogan's inner circle.
"Twitter, mwitter!," Mr Erdogan told thousands of supporters at a rally ahead of 30 March local elections late today, in a phrase translating roughly as "Twitter, schmitter!".
"We will wipe out all of these," said Mr Erdogan, who has said the corruption scandal is part of a smear campaign by his political enemies.
"The international community can say this, can say that. I don't care at all.
"Everyone will see how powerful the Republic of Turkey is," he said in a characteristically unyielding tone.
His office later said in a statement that Mr Erdogan was referring to what it called Twitter's failure to implement Turkish court orders seeking the removal of some links and that they may be left with no option but to ban the platform.
"If Twitter officials insist on not implementing court orders and rules of law ... there will be no other option but to prevent access to Twitter to help satisfy our citizens' grievances," the statement said.
Twitter said that it is looking into reports that its service has been banned in Turkey.
The Internet company published a message on its service advising users in Turkey that it was possible to send Tweets using mobile phone text messaging.