UAE telecom Du has blocked all websites deemed to offend the "moral, social and cultural values" of the Gulf Arab state, the company said on Sunday.
The move means from Monday companies operating out of Dubai's free zones and residents in Nakheel or Emaar Properties freehold developments will come under the UAE's proxy server for the first time.
According to the UAE Telecommunications Regulatory Authority (TRA), the proxy server blocks websites that contain pornography, alcohol, gambling, hatred, child abuse or terrorism.
However, many more sites than just those containing these subjects are covered by the proxy.
The move will raise concerns that media freedom is being restricted as many local and international media organisations have headquarters in Dubai Media City (DMC), one of the free zones to which Du provides telecoms and internet services.
Du informed customers of the change in its content filtering policy on Sunday via SMS text message.
"We wish to inform you that from April 14, 2008 we will be blocking sites with content that do not conform to the moral, social and cultural values of the UAE," Du said.
Du said in a statement to ArabianBusiness.com the change would bring its internet service in line with TRA guidelines.
Internet services offered by UAE incumbent telecom Etisalat have long been covered by the proxy server and TRA officials have said on several occasions over the past year that Du services would follow.
Censorship of the internet, common in much of the Arab world, has long been opposed by press freedom advocates and human rights groups that claim unrestricted access to information is integral to free expression.
Reporters Without Borders ranks the UAE 65th out of 169 countries in latest Press Freedom Index.