Bahraini activist Nabeel Rajab was sentenced to five more years in jail Wednesday over tweets critical of the war in Yemen.
Rajab is already serving a two-year sentence handed down last July for "disseminating rumours and false information" following critical comments he made on television about the government.
He played a key role in anti-government protests that sparked in 2011, following a wave of other revolts in the Arab world leading to his arrest.
Rajab was found guilty on Wednesday for insulting a neighbouring country and spreading "false news”, a judicial source told AFP on condition of anonymity.
Rajab walked into the courtroom with a "cheerful smile" and after being sentenced raised his hands to make a peace sign and laughed, according to AP.
In addition to tweets critical of the Saudi-led war in Yemen, he was also charged with comments about the treatment of inmates at the notorious Jaw prison, south of the capital Manama.
The kingdom's leading human rights groups - the Bahrain Center for Human Rights and the Bahrain Institute for Rights and Democracy - confirmed the charges and sentence.
Activists and human rights groups have condemned the ruling.
"It's time the Trump administration showed some spine in standing up to the dictatorship in Bahrain," said Brian Dooley, a senior adviser at the US-based group Human Rights First.
"It should take punitive action over this verdict and send the American ambassador to visit Rajab in prison to tell him that the US is on his side and against this reckless repression."
Protests erupted in Bahrain in 2011, led mostly by the country's majority Shia population who have long complained of discrimination.
A government crackdown - backed by a Saudi-led force - crushed large-scale protests in the country, although smaller demonstrations and unrest continue.