A Bahraini court has sentenced five men to 15 years in prison for two attacks by homemade bombs, including one during last year's Formula One race, the Gulf state's official BNA news agency says.
The sentencing on Monday came as Bahrain's public security chief said officials had foiled an attempt to smuggle explosives and arms, some made in Iran and Syria, into the country by boat.
BNA said the men had admitted being behind the bombings, but a monitor said they had pleaded not guilty to involvement in the attacks, which destroyed several vehicles but caused no injuries.
Two of the defendants were tried in absentia.
The defendants were also convicted of other counts relating to explosives, the agency said.
Mohammed al-Maskati, head of the Bahrain Youth Society for Human Rights, told Reuters news agency the men said to the court that their confessions during questioning were obtained under torture.
The authorities were not immediately available for comment on that allegation but have said that torture is not government policy.
The 2012 and 2013 Formula One Grand Prix have been marred by clashes between security forces and protesters.
Bahrain, home to the US Fifth Fleet, has been rattled by bouts of unrest since February 2011, when protests led by members of its Shia majority demanded that the Sunni ruling family give up ultimate power to an elected parliament.
Bahraini officials said on Monday that they had seized stocks of weapons and defused a car bomb during security raids on Saturday and Sunday.
Major-General Tareq al-Hassan, the public security chief, said authorities had captured 13 people wanted in connection with security cases aboard a boat police allege was smuggling them out of the island kingdom.
"According to the investigations, which revealed plans to carry out terrorist acts, security deployment has been intensified," Hassan said in comments published by BNA.
Plastic explosives, detonators, automatic rifles and ammunition were found in a warehouse and onboard a second boat intercepted as it was heading to the country.
Hassan said authorities defused the car bomb in the Hoora area of the capital Manama.
"Fifty hand grenades made in Iran," as well as "295 fuses connected to switches labelled as made in Syria," were found in the nine-metre vessel, he said.
Dozens of C4 and TNT explosive devices were also found on the boat, he said, without providing details about the source of the alleged shipment.
Bombs have become more frequent in Bahrain as the anti-government opposition campaign wears on.