A Bahraini court sentenced 12 Shiites on Sunday to 10-year jail terms after convicting them of trying to kill policemen in a village near the capital, a judicial source said.
Another defendant was handed down a three-year prison sentence and four more were acquitted.
The 17 had all been charged with attempted murder of police officers, taking part in an unauthorised demonstration and possessing petrol bombs.
They were arrested after unrest on May 1, 2012 in a Shiite village where a policeman suffered burned hands when his patrol was attacked.
In a separate case in another Manama court on Sunday, a policeman was acquitted of attempting to murder a protester because of insufficient proof, the source said.
The officer, a Pakistani employed by the interior ministry, was charged after Saleh Abbas, a Shiite, was shot dead during a demonstration in Shakura village on April 19 last year.
The source said lawyers cited medics as saying the dead man was hit in the heart, lung, stomach and spleen by buckshot.
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Under cross-examination, the policeman admitted he was the only member of his patrol to have opened fire on the day of the killing, lawyers said in challenging the acquittal.
A Shiite-led uprising to demand democratic reforms in Sunni-ruled but Shiite-majority Bahrain was crushed in March 2011.
King Hamad in August this year ordered stiffer penalties for "terror acts".
These include a minimum 10-year jail term for an attempted bombing. If such attacks cause casualties, the sentence can be life imprisonment or the death penalty.
The authorities have also banned demonstrations in Manama.
Strategically located across the Gulf from Shiite Iran, Bahrain is home to the US Navy's Fifth Fleet and is an offshore financial and services centre for its oil-rich Arab neighbours.
At least 89 people have been killed since the protests began, according to the International Federation for Human Rights.