At least 1,000 people were killed in Bangui, the capital of the Central African Republic, in just two days of violence earlier this month, according to Amnesty International. The figure is significantly higher than an earlier UN estimate.
Seleka, a Muslim-militia outfit, ousted Christian President Francois Bozize in March and installed their leader Michel Djotodia as the country's interim president.
This sparked a sectarian conflict as Anti-Balaka, the Christian militias loyal to Bozize, raided Muslim neighbourhoods and killed about 60 Muslim men.
Following this, Seleka's men unleashed retaliatory attacks, killing 1,000 people in Bangui.
Earlier, the UN had estimated that about 450 people were killed in Bangui, while another 150 died in separate incidents in different parts of the country.
"The de-facto government forces, known as ex-Seleka, retaliated on a larger scale against Christians in the wake of the attack, killing nearly 1,000 men over a two-day period and systematically looting civilian homes. A small number of women and children were also killed," the Amnesty report said.
Violence has also spread to other parts of the country. Bossango, 300 km north of Bangui, is also deserted due to the religious violence in the country, Pakistan's Dawn reports.
Residents of Bossangoa have fled to a large camp near the archbishop's office.
"Spontaneously and in waves, in the past two months, 40,000 Christians in Bossangoa and surrounding villages have gathered around the archbishopric, crammed onto only four hectares," an official from the aid group Action Against Hunger said.
A mere 800 metres away, thousands of Muslims have also camped on the grounds of the Liberte school.
The Amnesty report says that civilians are being massacred and war crimes continue to be committed in the country, despite the presence of French and African Union troops which are engaged in trying to disarm the militia.
As many as 1,600 French troops are deployed in CAR, while the African Union has authorised an increase in the number of its troops to 6,000.
"The brutal killings in the Central African Republic are creating a cycle of murder and reprisal that threatens to spin out of control," Peter Bouckaert, author of a Human Rights Watch report on CAR violence, told the BBC.
The watchdog also urged the UN to send a peacekeeping mission to CAR.
"The UN Security Council needs to act quickly to bring this evolving catastrophe to a halt," said Bouckaert, adding: "The potential for further mass violence is shockingly high."