With the exception of Ethiopia, which blocks a number of political and security-related websites, and a few cases of isolated Internet censorship related to political events, most of sub-Saharan Africa has historically been free of technical filtering. This week, however, the government of Uganda wrote to the heads of three of the country's major ISPs asking them to block Facebook and "Tweeter" [sic] "to eliminate the connection and sharing of information that incites the public."

The request comes on the heels of a week of opposition protests over rising fuel and food prices. The protests have been widely advertised on Twitter using the hashtag #walk2work, and opposition leaders Kizza Besigye and Norbert Mao, among others, have been repeatedly arrested.

Several contacts in Uganda are reporting that, as of Monday, the sites are accessible, though one contact reports that both Facebook and Twitter were temporarily inaccessible through Uganda Telecom on Friday. Uganda's Observer newspaper is reporting that access has been suspended.

Last week, Uganda's Commissioner of Police called for the government to "guard against misuse of communication networks to protect social values and national identity," pointing to the Ugandans at Heart blog, which covers political and social issues in the country, and its associated Ugandans at Heart Google Group as examples of sites that "pose a serious national security threat if their net publications are not regulated."