Iran has blocked access to Google search and Gmail in a move officials say is aimed at improving cyber security.
The Islamic Republic has increasingly tightened cyber security after its nuclear programme was targeted by the Stuxnet worm in 2010, but Iranians fear the move is the country’s latest attempt to control their internet access.
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According to the Iranian Students' News Agency (ISNA), the Google ban is connected to the controversial anti-Islamic film posted on the company's YouTube site, but there has been no official confirmation.
An official announcement at the weekend said: "Google and Gmail will be filtered nationwide, and will remain filtered until further notice."
Iran already prevents ordinary citizens from accessing countless sites on the official grounds they are offensive or criminal, according to the Telegraph.
But Iranians say many of the controls are aimed at blocking access to sites such as Facebook and YouTube because they can be used to voice anti-government protest.
In March, UK foreign secretary William Hague expressed concerns about censorship in Iran following the blocking of the ‘UK for Iranians’ website. He condemned the action as part of Iran's ever-tightening stranglehold of censorship.
Iranians typically bypass filters by using virtual private networks that allow web access behind heavily encrypted firewalls, but reports indicate that Iran is planning to connect all citizens to a national information network by March 2013.
But the reports said it is not clear whether access to the global internet would be cut once the national Iranian information network is in place.
Last month, communications and technology minister Reza Taqipour said lran needed to develop its own network to ensure the safety of the country's information.
However, some commentators do not think the services are going to stay restricted for long.
An Iranian telecommunications consultant living in Germany told the BBC that he thinks the move is just a propaganda tool to demonstrate that Iran is doing something against the US, but it is unlikely to last longer than a few days.
It is not the first time Iranian authorities have cut access to Google services, only to restore them some time later.