Paul Doany, head of Turk Telekom, Turkey's largest telecommunications provider, said his company had begun immediately 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 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."
A group of Turkish activists and Internet users has set up a website to petition the lift of the ban at www.youtubeyasagi.com
They alleged that a ban wouldn't solve the problem and can't be effective in todays cyber communication world. Such a ban should be considered as a curb on users freedom, they said.
At the same time, Doany said Turk Telekom would allow access to the popular video sharing site again if the court decision were rescinded.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. The CNN-Turk Web site featured a link allowing Turks to complain directly to YouTube about the "insult."
On its front page on Wednesday, the newspaper Hurriyet said thousands of people had written 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.(EÜ)