Turkey has restricted access to Twitter hours after the prime minister, Tayyip Erdogan, threatened to shut down the social media platform after users published claims of corruption against him.
Users reported on Friday that they were forwarded from twitter.com to a statement from Turkey's telecoms regulator, TIB, which cited court orders for the site's apparent closure.
The statement cited four 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 Erdogan's inner circle.
The state-run Anatolia news agency said authorities "technically blocked access to Twitter" because the service had ignored the orders to remove some links deemed illegal, the AFP news agency reported.
Twitter said that it was investigating, but had not issued a formal statement. The company did post a message instructing Turkish users on how to continue using the service via SMS text message.
Erdogan on Thursday promised to "root out" and "wipe out" Twitter services, which he said has helped his political enemies conduct a smear campaign against him.
"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.
Leaked recordings shared and linked on Twitter include one in which Erdogan allegedly instructs his son to dispose of large amounts of cash from a residence amid a police corruption probe.
Erdogan insists the recordings are fabricated "vile fakes" and part of a plot to discredit the government ahead of the March 30 elections.
Following his speech, Erdogan's office said he 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.
The apparent blocking was only the latest clash between Turkey's ruling party and social media companies including Google, Facebook and Twitter.
After a series of popular protests partly fuelled by Twitter last summer, Erdogan slammed the service as "a scourge".
Erdogan said two weeks ago that Turkey could also ban Facebook and YouTube, which he says have been abused by his enemies after a stream of audio recordings purportedly revealing corruption in his inner circle emerged online.