The head of Arab TV channel Al Jazeera said on Tuesday he was leaving the network, but gave no reason for his departure.

"I have decided to move on," the network's director-general Waddah Khanfar said in a resignation note emailed to Al Jazeera staff and also publicised on social media site Twitter.

"For some time I have been discussing my desire to step down with the chairman of the board. He has kindly expressed understanding and has accepted my decision."     

Since it was launched in 1996, Al Jazeera has become the highest-profile satellite news broadcaster in the Middle East.

It has frequently had difficulties with Western and Arab governments in a region where governments have traditionally kept tight control over state media.    

Al Jazeera, owned by the Qatari government, aired round-the-clock coverage of uprisings that brought down veteran rulers in Tunisia, Egypt and Libya this year, and the station promotes itself as a democratic voice in the region.- Reuters