Access to the popular video-sharing website YouTube has been suspended in Turkey following a court order.
The ban was imposed after prosecutors told the court that clips insulting former Turkish leader Mustafa Kemal Ataturk had appeared on the site.
According to Turkish media, there has been a "virtual war" between Greek and Turkish users of the site, with both sides posting insulting videos.
The clip prompting the ban reportedly dubbed Ataturk and Turks homosexuals. Insulting Ataturk, the founding father of modern Turkey, or "Turkishness" is an offence which can result in a prison sentence.
The offending videos sparked a storm of complaints to YouTube and the clips were removed, but the court order goes further, blocking all access to the site.
Paul Doany, head of Turk Telekom, Turkey's largest telecommunications provider, said his company had immediately begun enforcing the ban.
"We are not in the position of saying that what YouTube did was an insult, that it was right or wrong," Doany said Wednesday in remarks to the state-run Anatolia news agency. "A court decision was proposed to us, and we are doing what that court decision says."
Visitors to the YouTube site from Turkey were greeted with the message: "Access to this site has been blocked by a court decision!..."
The vast majority of Turkish Internet users use Turk Telekom, a state-run monopoly until it was privatized in 2005.
A message in both Turkish and English at the bottom of the page said, "Access to www.youtube.com site has been suspended in accordance with decision no: 2007/384 dated 06.03.2007 of Istanbul First Criminal Peace Court."
Turk Telekom petition
The court -- acting on a petition from Turk Telekom -- ruled later on Wednesday that it would revoke the ban as soon as it ascertained that the offending videos had been removed from YouTube. YouTube is owned by internet search engine giant Google.
Earlier, Doany said Turk Telekom would allow access to the popular video sharing site again if the court decision were rescinded. Access from Turkey might be possible through other service providers, he said.
Over the past week, Turkish media publicized what some called a "virtual war" between Greeks and Turks on YouTube, with people from both sides posting videos to belittle and berate the other.
The video prompting the ban allegedly said Ataturk and the Turkish people were homosexuals, news reports said.
On its front page on Wednesday, the newspaper Hurriyet said thousands of people had written to YouTube and that the Ataturk videos had been removed from the site. "YouTube got the message," the headline said.
Insulting Ataturk or "Turkishness" is a crime in Turkey punishable by prison.
Turkey, which hopes to join the European Union, has been roundly condemned for not doing enough to curb extreme nationalist sentiments and to protect freedom of expression.