Abd al-Hadi al-Khawaja, head of the now-banned Bahrain Centre for Human Rights, appeared before a court in the capital Manama under tight security on Saturday.
He received a hero's welcome from about 200 supporters packed inside the courtroom and hallway, who shouted "Long live Abd al-Hadi!" and called for the resignation of Prime Minister Shaikh Khalifa bin Salman al-Khalifa, whom they accused of corruption.
The judge adjourned the session until Wednesday after reading the charges, which included defamation and spreading "false information that could damage public interests".
The defendant rejected the charges before he was whisked away back to prison amid angry cries from his sympathisers.
Khawaja was jailed last month after he made a speech blaming Shaikh Khalifa for Bahrain's economic woes, and calling on him to step down after having spent three decades in his post.
His detention and the consequent closure of his human-rights centre has provoked criticism from international rights groups and key ally, the United States, whose navy has its Fifth Fleet stationed in Bahrain.
Bahrain is the least wealthy of the Gulf Arab states, with high unemployment and a history of political tension.
King Hamad bin Isa al-Khalifa has stood by the prime minister - who is also his uncle - and says he will not tolerate criticism of senior government officials.