(CNN) -- At least 40 members of a religious minority in Myanmar were killed by security forces and Buddhists in the western village of Du Char Yar Tan last week, a human rights group said.
Fortify Rights, a group based in Southeast Asia, claims the attacks against the Rohingya Muslims were carried out after the suspected killing of a police officer, who is still missing. Most of dead were women and children, the group said.
But the government denies the killings, and Myanmar's deputy minister of information told reporters that the news outlets reporting them are "wholly and totally wrong."
In a statement, the government outlined the details of an incident that led to the missing police officer at the center of the latest clashes.
It apparently started January 13 when a police patrol led by the missing officer encountered a group of men described in the report as Bengalis "sitting around a fire in front of shops." The group apparently started throwing stones at the patrol and was joined shortly after by about 100 villagers with knives and sticks, according to the report.
The officers fled, except for police Sgt. Aung Kyaw Thein, who has been missing since. Riot police have moved into the village, and journalists and human rights activists have been denied access, according to Fortify Rights.
"When the police went into the village to find the missing police, almost all the men had fled, leaving women, children and old people," a police spokesman told CNN. He said there are so many security forces now looking for the missing police officer that violence between Muslims and Buddhists is no longer possible.
Valerie Amos, United Nations under-secretary-general for humanitarian affairs, warned of "alarming levels of violence, including the killing of many civilians and a policeman." She called on Myanmar's government to launch an impartial investigation into the claims.
The U.N. calls the Rohingya Muslims one of the most persecuted populations in the world, and 3,500 of them live in the village of Du Char Yar Tan.
They've been the frequent targets of violence by Buddhists, who are the majority in Myanmar.
U.S. President Barack Obama urged Myanmar's President Thein Sein during a visit to the White House last year to respect the rights of the Rohingya minority.