A Bahraini court yesterday jailed the head of the teachers' union for 10 years and his deputy for three.
They were among a string of Shiites sanctioned over their role in anti-regime protests, the BNA state news agency said.
The verdicts came a day after the kingdom held by-elections, boycotted by the Shiite-led opposition, to replace 18 Shiite MPs.
They quit the parliament in protest at the violence used against demonstrators in February.
The teaching union chiefs, Mahdi Abu Deib and Jalila Al Salman, were convicted by the court of national safety of "calling to forcefully overthrow the regime in union statements", BNA said. They were also accused of "promoting hatred to the regime and spreading false news".
BNA said the pair used the union to "instigate acts that are considered criminal like - calling for sit-ins by teachers, obstructing teaching, holding protests near schools ... and calling upon parents not to send their children to school".
The court was established after King Hamad declared an emergency law in mid-March, a day before quashing a month-long pro-democracy protest.
Meanwhile, BNA reported that in a different case, the court sentenced to 15 years in jail six men convicted of chopping the tongue of an Asian muezzin who calls for prayer.
Two other men were jailed for 10 years in that case.
Many Asians complained of attacks by alleged members of the Shiite majority, who accuse the Sunni ruling family of Bahrain of naturalising Asian Sunnis to tip the demographic balance.
Three others were jailed for three years and a fourth for one year for hiding two wanted persons, BNA also reported.
Another Shiite was sentenced to three years for not reporting the running over of two policemen and for "inciting hatred against the regime and taking part in public gatherings with the aim of disturbing security".
Authorities said that in May, 405 detainees had been referred to courts, while 312 were released.