|Michael Posner of the US state department attended the trials of 48 medics in Manama [EPA]
Three young women arrested by Bahraini police while holding a sit-in protest at the UN offices in Manama have been released, the United Nations said.
"The United Nations Development Programme in New York has been advised that three women who conducted a peaceful protest at the organisation's offices in the capital Manama have been released by police and that charges will not be pressed," the UNDP said in a statement on Wednesday.
It said the UNDP had made "urgent representation to Bahrain's authorities to release the three women," and that the UN agency had "launched a formal investigation into how the incident at its office was handled".
The Bahrain Youth Society for Human Rights had said on its website that the women, including Zaineb al-Khawaja, daughter of activist Abdelhadi al-Khawaja, were detained three hours into their sit-in.
They were protesting against the arrest of family members and delivered a letter to UN chief Ban Ki-moon calling for their release, it said.
Bahraini authorities in mid-March crushed a month-long protest movement on the streets led by Shia demonstrators calling for democratic reform in the Sunni-ruled state.
Elsewhere on Wednesday, Michael Posner of the US state department, said American officials were concerned about claims of abuses against detainees following Bahrain's crackdown on protesters.
Posner, the assistant secretary of state for democracy, human rights and labour, expressed hopes
for proposed talks next month between Bahrain's Sunni rulers and opposition groups.
"The challenge now is how to initiate dialogue with representatives of all sides and to ensure that this dialogue will address and resolves divisive issues."
Posner also called for transparency during the forthcoming trials of dozens of people charged with illegal activities during the protests.
The assistant secretary of state, who spent four days in Bahrain, attended the contentious trial on Monday of 48 medics facing charges ranging from incitement to storing weapons to taking over a hospital.
The medics - who helped treat pro-democrracy protesters wounded in the state's crackdown - are accused of supporting the protests against the rulers.
At least 31 people have died since the unrest in the country began in February.