Image courtesy: Twitter

DUBAI: Amnesty International on Tuesday urged Bahraini authorities to release a detained human rights activist it said was at "high risk of torture".

Ebtisam Al-Saegh had retweeted a post on Monday criticising security forces' treatment of women and blaming the king.

Amnesty said she was arrested at her home Monday night and taken to a prison in Manama. "We fear that she is at high risk of torture as long as she remains in custody," it added.

The rights group said Al-Saegh had been "beaten and sexually assaulted by members of the Bahraini National Security Agency" during a previous arrest in May.

Bahraini authorities have failed to investigate those claims, it said.

The tiny Gulf kingdom has been rocked by persistent unrest since 2011 when some tried demanding a constitutional monarchy and an elected prime minister.

Authorities have detained and tried hundreds of protestors and cracked down hard on opposition groups despite appeals by international rights groups.