Bahraini security forces have beaten children and threatened them with rape and electric shocks after detaining them in protest-related cases last month, the anniversary of a 2011 pro-democracy uprising, rights groups said on Wednesday.

A government representative did not comment on the specifics of the accusations but told Reuters in a statement that Bahrain took protection of human rights “extremely seriously” and had a “zero-tolerance policy” of mistreatment in the justice system.

In a joint statement, Human Rights Watch (HRW) and the London-based Bahrain Institute for Rights and Democracy (BIRD) said about 13 children aged between 11 and 17 were held in early to mid-February as authorities tried to dissuade protesters from gathering to mark the 10th anniversary of the uprising.

“Five children, arrested on Feb. 14-15, said that police from the station beat, insulted, and threatened them with electric shocks from a car battery,” the two groups said.

“An officer hit a 13-year-old on his head and threatened to rape him, give him electric shocks, and beat his genitals.”

In some cases, the rights groups said, Bahraini police arrested children accused of burning tires or blocking a road on the day of their arrest. Police also accused children of vandalism, planting a fake bomb and throwing petrol bombs in November 2020, they added in the statement.

Four of the children remain in detention, including a 16-year-old with a serious medical condition, New York-based HRW and BIRD said.

In a statement on Wednesday, Bahrain’s attorney general directed the public prosecution to adopt the aims of a law on corrective justice for children and their protection issued on Feb. 18 and intended to take effect six months later.

A Bahrain government source told Reuters that a criminal court on Thursday handed six-month jail sentences to five people aged between 15 to 18 at the time of the offence, but ordered alternative punishment so as to adopt the aims of the new law.

The source said four had been tried under one case and the fifth in a separate case. The source could not confirm whether the cases were the ones referred to by HRW and BIRD.

It was not immediately clear what the alternative punishment would be, but authorities have said that non-custodial sentences include community service and repairing criminal damage.

Bahrain’s U.S.-backed, Sunni Muslim monarchy used force to suppress the 2011 uprising, led mostly by the Shi’ite Muslim community, and cracked down on sporadic unrest and dissent later. It was the only Gulf state to experience one of the “Arab Spring” uprisings a decade ago.

Mass trials followed and thousands were imprisoned, with many others fleeing abroad. Subsequently there have been clashes between protesters and security forces, who have been targeted by bomb attacks.

Rights groups including Amnesty International have criticised the kingdom’s lack of an independent judiciary and accused its security forces of committing torture and other forms of ill-treatment with impunity.

The government denies the charges.