Two of the convicts, one of whom was tried in absentia, were jailed for carrying out a bomb attack targeting police in a Shiite village near Manama two years ago, said prosecutor Ahmed al-Hammadi.
The attack had caused damages but left no casualties, he said in a statement carried by the official BNA news agency.
In the second trial the same criminal court jailed a third defendant of opening fire at policemen last year in another Shiite town wounding one of them, Hammadi said.
The defendants were not identified but dozens of Shiites have been put on trial and handed lengthy jail terms in the Sunni-ruled kingdom during the past five years.
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The criminal court yesterday sentenced three people to life in prison for possessing weapons which they planned to use to carry out a "terrorist" plot.
Bahrain had been shaken by unrest since it quelled a month-long Shiite-led uprising demanding reforms which erupted on February 14, 2011.
Tiny but strategic, the kingdom is connected to regional Sunni powerhouse Saudi Arabia by a causeway, lies across the Gulf from Shiite Iran and is home to the US Fifth Fleet.