Three men in the Kingdom have been jailed for 15 years for two homemade-bomb attacks.

Bahrain said on Tuesday it was investigating torture claims by three men jailed for 15 years for two homemade-bomb attacks – including one during last year’s Formula 1 car race.

On Sunday, five men – including two who were tried in absentia – were convicted by a court for their role in the blasts, which destroyed several vehicles but caused no injuries, according to the Gulf Arab state’s official BNA news agency.

BNA said the men had admitted being behind the bombings but the men’s lawyer, Jassim Sarhan, told Reuters they pleaded not guilty to involvement in the attacks and told the court their confessions during questioning were obtained under torture.

“The Kingdom of Bahrain does not and will not tolerate any form of torture or mistreatment. The Special Investigation Unit (SIU) did receive complaints from the defendants,” the government’s Information Affairs Authority (IAA) said in an emailed statement to Reuters.

“The SIU takes these allegations very seriously and have looked into these claims. Their investigation is currently ongoing. We can’t give further information until the investigation is completed.”

Bahrain, home to the U.S. Fifth Fleet, has been in political turmoil since a 2011 uprising led by majority Shi’ites who demand more say in running the kingdom, which is ruled by the Sunni Muslim al-Khalifa dynasty.

Widespread and excessive force, including confessions under torture, was detailed in a report by an international human rights commission led by Cherif Bassiouni, a prominent Egyptian-American jurist.

The Bahrain government says it has taken steps to address security forces actions, but activists say abuses continue.

The SIU was set up as part of the Bassiouni commission’s recommendations.

The Manama government quelled the 2011 revolt in the island Kingdom, but almost daily protests and small-scale clashes continue, and bomb attacks have been increasing since mid-2012.