Twelve members of an armed group died in a clash with UN peacekeepers and government troops in northeastern Central African Republic (CAR), the authorities said on Tuesday.

The fighting erupted on Sunday after the Popular Front for the Rebirth of Central Africa (FPRC) entered the flashpoint town of Birao before being repelled, government spokesman Ange-Maxime Kazagui said in a statement.

"The toll is 12 dead on the FPRC's side," he said.

The UN force MINUSCA, in a statement, said "heavily armed" FPRC fighters entered the town before being pushed back. The FPRC is one of the largest armed groups in the CAR, a land-locked impoverished country where militia groups control most of the territory, often fighting for control over resources.

The FPRC took over the crossroads town of Birao in 2014, giving it control over the lucrative tax of goods from neighbouring Sudan. Violence erupted in July between the FPRC and the Movement of Central African Liberators for Justice (MLCJ), which is mainly drawn from the Kara ethnic group. The MLCJ currently has control of the town but outbreaks of fighting remain frequent.

Kazagui, in his statement, said the FPRC had entered Birao from three directions, apparently threatening a site for displaced people and an army base. Last Thursday, MINUSCA asked France to send warplanes over Birao to dissuade the FPRC from mounting an attack, the UN force's spokesman, Vladimir Monteiro, said on Saturday.

Both militias are among the signatories of a February 2019 peace agreement between the government and armed groups. Thousands of people have been killed and nearly a quarter of CAR's population of 4.7 million have been displaced by conflict since 2013. The former French colony is bracing for presidential elections in December.