Yangon - Several people including women and a child have been killed in an attack on Rohingya Muslims in strife-torn western Myanmar, a rights group said on Friday, as the US embassy voiced alarm.
Myanmar's Rakhine state remains extremely tense after several outbreaks of communal bloodshed between Buddhist and Muslim communities since 2012 that have killed scores and displaced some 140 000 people, mainly from the Rohingya minority.
Details of the latest unrest were unclear, but Rohingya activists said at least two women and a child were stabbed to death in an attack on a village near the border with Bangladesh earlier this week, with possibly several dozen casualties.
Myanmar authorities denied any civilian deaths but confirmed a clash took place in which a police officer was presumed to have been killed.
Chris Lewa, the Bangkok-based director of The Arakan Project, which lobbies for Rohingya rights, said the attack on the village of Du Chee Yar Tan on Monday happened sometime after the initial clash with police.
"There were people killed, mostly women and children", she told AFP, but added that reports from sources in the area on the number of people killed varied widely, from around 10 to several dozen.
The US embassy in Yangon said on Twitter that it was "deeply concerned" about the violence "especially reports of excessive use of force by security officials".
"We urge [the] government to thoroughly investigate, bring perpetrators to justice, and ensure equal protection and security under the law in Rakhine", it added.
Lewa said one villager, who has worked with The Arakan Project, reported seeing the bodies of two women and a 14-year-old boy with stab wounds after returning to the village days after the unrest.
She said the use of knives suggested the involvement of local Rakhine Buddhists, who have repeatedly clashed with the Rohingya, rather than the police.
Local police denied any villagers had died, but said authorities had come under attack on Monday without giving any reason why.
"A police sergeant is still missing along with his weapon. We are looking for him", a senior police official in nearby Maungdaw town told AFP on condition of anonymity.
Another police officer in the state capital Sittwe said dozens of people had been rounded up after the unrest, with 10 still in custody.
Myanmar's government considers the estimated 800 000 Rohingya in the country to be foreigners while many citizens see them as illegal immigrants from Bangladesh and view them with hostility.