Ethiopia - Campaigners have warned of fresh efforts by the Ethiopian government to clamp down on certain types of internet use in the country.

Reporters Without Borders says that the authorities have installed a system to block access to the Tor network - a "hidden" layer of the internet, used to allow anonymous online communications.

Users already face up to 15 years in jail if they use Skype or similar internet call services.

Addis Ababa has not provided a comment.

"The Ethiopian government is trying to attack every means of information exchange," Ambroise Pierre from the Reporters Without Borders Africa service told BBC News.

"There's already a very strict control over written press, and last year several journalists were arrested, and now the government is tackling communications over the internet.

"More and more people in Ethiopia are turning to new technologies, and some are even able to bypass censorship, which explains why the government is trying to use effective methods to control internet communications."