"A citizen is going to have his head cut off over tweets on an anonymous account with less than 10 followers," one rights group said.

Saudi Arabia has sentenced to death a government critic who denounced alleged corruption and human rights abuses on social media, his brother and others familiar with the case told AFP on Monday.

The judgement was handed down against Mohammed al-Ghamdi in July by the Specialized Criminal Court, a secretive institution established in 2008 to try terrorism cases that has a history of unfair trials resulting in death sentences.

The charges against al-Ghamdi include conspiracy against the Saudi leadership, undermining state institutions and supporting terrorist ideology, sources briefed on the details of the case told AFP.