By Stephanie Nebehay
GENEVA (Reuters) - U.S. police and security forces must not use disproportionate force against protesters and journalists in U.S. cities including Portland or detain them unlawfully, the United Nations human rights office said on Friday.
Law enforcement officers and federal forces must be clearly identifiable so that they can be held to account for any incidents of abuse, it said.
U.S. cities including Portland have been rocked by protests against racial injustice sparked by the death of George Floyd in police custody in Minneapolis on May 25.
"It is very important that people are able to protest peacefully, that people aren't subject to unnecessary, disproportionate or discriminatory use of force," Liz Throssell, U.N. human rights spokeswoman, told a Geneva news briefing.
Citing reports that peaceful protesters have been detained by "unidentified police officers", she voiced concern that such detentions may give rise to arbitrary or unlawful detention.
"The authorities should ensure that federal and local security forces deployed are properly and clearly identified and would use force only when necessary, proportionately and in accordance with international standards," Throssell said.
"It is very important when there is an incident then it can be traced back to who is responsible," she said.
"Any victims of unnecessary excessive use of force" have the right to prompt and transparent investigations, she added.
The U.S. Justice Department said on Thursday it would investigate the use of force by federal agents against protesters in Portland after another night of unrest in which Mayor Ted Wheeler was tear-gassed.
The investigations follow public anger over the deployment of federal border patrol officers to Portland against the wishes of local officials, and President Donald Trump's administration has said it is sending a similar contingent to Seattle.
(Reporting by Stephanie Nebehay; Editing by Hugh Lawson, William Maclean)