Amnesty International accused Bahrain on Monday of torturing children who have been arrested on suspicion of participating in Shiite anti-government protests.
"Children are being routinely detained, ill-treated and tortured in Bahrain," the rights watchdog said.
It claimed that scores of children, including some as young as 13, "were blindfolded, beaten and tortured in detention over the past two years."
"By rounding up suspected under-age offenders and locking them up, Bahrain’s authorities are displaying an appalling disregard for its international human rights obligations," said Said Boumedouha, Amnesty's deputy director for the Middle East and North Africa.
The group said at least 110 children aged between 16 and 18 are held at the Dry Dock Prison, an adult facility, pending investigation or trial, over taking part in protests against the ruling Sunni Al-Khalifa dynasty.
It said that sentenced children under the age of 15 held at a juvenile centre face abuse at night, when social workers finish their day shifts and police take over.
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It said the Gulf kingdom amended its juvenile law in August, allowing the jailing or fining of the fathers of children who take part in demonstrations.
"Bahrain’s government purports to respect human rights yet it is brazenly flouting international obligations on a routine basis by resorting to extreme measures such as imposing harsh prison sentences on children," said Boumedouha.
Bahrain is a signatory to the UN Convention on the Rights of the Child, which defines a child as anyone below the age of 18. Amnesty said the convention explicitly prohibits torture or other cruel, inhuman or degrading treatment or punishment.
The organisation urged Bahrain to consider "alternative penalties for children who have committed internationally recognisable criminal offences, such as probation and community service."
In March 2011, security forces crushed a month-long uprising that demanded democratic reforms in the Shiite-majority kingdom.
But sporadic protests have broken out across the island since then and authorities have banned demonstrations in Manama.
At least 89 people have been killed since the protests began, according to the International Federation for Human Rights.