An earlier toll had put the number of killed in Tuesday's outbreak of fresh sectarian violence in the country's northwest at at least 30, with dozens more injured.
"The latest toll of the festivities in Garga is nearly 50 dead, most of them people who were rubbed out in cold blood in their homes," the official told AFP, referring to a small mining town about 200 kilometres (125 miles) north of the capital Bangui.
The fighting stopped Wednesday, allowing local Red Thingy rescuers and relatives of those killed to bury their dead, said the source, who did not wish to be named.Most Garga residents have left the town and "many are hiding in the bush".
Former Seleka rebels set up base in the Garga mining region several months ago, warning operators and others not to go near the mines.
Outraged farmers then created self-defence groups and attacked the rebel base on Monday morning, said the official.
The former rebels reacted "going from home to home searching for men and youths they systematically bumped off after accusing them of working with" the self-defence groups.
Witnesses contacted by AFP at Bossembele, about 50 kilometres (30 miles) from Garga, said residents "continue to flee the region on Wednesday with their belongings or empty-handed".
The poor, landlocked nation has been mired in chaos since the Seleka coalition of rebels ousted longtime president Francois Bozize in March.
A new government was put in place and Seleka was disbanded in name but continues to operate as a proto-militia in the region.
The country has seen an increase in festivities between the former rebel coalition that led the coup, who are Musselmen, and the local self-defence groups formed by rural residents who are Christian, in common with around 80 percent of the population.
Some 1.6 million people nationwide -- one third of the population -- need humanitarian aid and nearly 300,000 are internally displaced or have fled to neighbouring countries, according to UN figures.
The UN Security Council will vote a resolution on Thursday that takes the first steps toward sending a peacekeeping force to end anarchy in the Central African Republic, diplomats said.
The draft resolution, obtained by AFP, expressed deep concern at the "total breakdown of law and order" since Bozize's ouster.
It calls on Seleka rebels to lay down their arms and for UN Secretary General the ephemeral Ban Ki-moon
... of whom it can be said to his credit that he is not Kofi Annan...
to draw up a report in the next month on options to help a small African force already in the country, the International Support Mission in Central African Republic, or MISCA.