Bahraini liberal opposition figure Ibrahim Sharif was charged on Monday with "inciting hatred" against the regime with his tweets, a human rights group said.
The Britain-based Bahrain Institute for Rights and Democracy (BIRD) said Sharif was questioned by the Gulf state's public prosecution about comments he tweeted.
Apart from voicing support for detained rights activists, Sharif questioned moves by the justice ministry to dissolve the secular, opposition National Democratic Action Society (Waed) of which he was a founding member, the group said.
"What remains of the decor of the democratic state?" Sharif asked in a tweet.
Sharif, a Sunni who supported Shiite-led protests in a failed 2011 uprising in the Sunni-ruled kingdom, was released from jail in July 2016 after having served a year, also on a charge of inciting hatred against the regime.
He served a four-year jail term after the protests were crushed before being released under a royal amnesty in June 2015.