DUBAI (Reuters) - Rights group Amnesty International said a court in the United Arab Emirates had sentenced a dissident professor to 10 years in prison for online activism on Wednesday, calling the move a violation of free speech.

State news agency WAM reported that an appeals court in the capital Abu Dhabi had sentenced an Emirati national, referred to only by the initials N.A.G., for social media activity.

It quoted the court as saying the sentence was for “communicating with secret organizations linked to the Muslim Brotherhood, by creating accounts on social media and publishing photos and articles that are offensive to the state’s symbols and values, its internal and foreign policies and its relations with an Arab state”.

Amnesty International identified the sentenced man as prominent dissident Nasser bin Ghaith.

“By imposing this ludicrous sentence in response to his peaceful tweets, the authorities have left no room for doubt: those who dare to speak their minds freely in the UAE today risk grave punishment,” Amnesty’s statement quoted its Middle East research deputy director Lynn Maalouf as saying.

It was not immediately clear which posts by bin Ghaith, who frequently posted on his Twitter account before his arrest in August 2015, had led to his conviction.

A tourism and trade hub, the UAE brooks little public criticism of its monarchy or policies and is especially opposed to the Islamist ideology of the Muslim Brotherhood.