Human Rights Watch accused Libya on Thursday of blocking access to YouTube and other independent or opposition websites, saying it signalled a return to the "dark days" of total media control in the north African country.
It said YouTube was no longer available after footage of family members of Libyan leader Muammar Gaddafi and of demonstrations in the eastern city of Benghazi were posted on the online video site.
Since Jan. 24 the government had also blocked access to opposition websites based abroad, a source of independent news in a country dominated by state media, Human Rights Watch said.
"With editors based abroad and journalists in Tripoli and Benghazi, these websites regularly publish news on sensitive subjects including human rights abuses by the Libyan government," said HRW's Middle East director Sarah Leah Whitson.
Libyan government officials had no immediate comment.
A group of Libyan bloggers, journalists and rights defenders have begun an online campaign on social networking site Facebook demanding the authorities restore access to the sites.
"These web sites were the one recent sign of tangible progress in freedom of expression in Libya," Whitson said in a statement. "The government is returning to the dark days of total media control."
Libya's only two private newspapers Oea and Quryna stopped publishing last month after the General Press Authority refused to continue printing, citing non-payment of bills.
Oea and Quryna have written about official corruption and demanded reform, marking them out from a state-controlled media deferential to the government.
"Libyan authorities should be increasing the number of private newspapers rather than stopping their circulation," Whitson said.