The peace pact, negotiated in the Sudanese capital of Khartoum before being signed in Bangui on February 6, bought together President Faustin-Archange Touadera and the leaders of the 14 armed groups who control most territory in the African nation.

On Monday, one of the main militia groups, the Union for Peace in the Central African Republic (UPC), led by Ali Darassa, said the peace deal was "threatened if the government does not show a clear change of attitude".

A UPC representative had been appointed Minister of Livestock in the new government.

Another group, the Democratic Front of the Central African People (FPDC) announced it was walking away in protest at the newly formed government.

The FPDC "is resolved purely and simply to withdraw from the peace process," it said in a statement sent to AFP.

The group, whose stronghold is in the northwest, protested that the new government formed on Sunday was "far from being inclusive".

In a video released on social media on Monday, Prime Minister Firmin Ngrebada said the government would "follow the arrangements" of the peace agreement and criticised militias for demanding too many posts.

"Today we have a government of 36 members, it was not possible to bring five members of each armed group into government, it would be too bloated," the premier said.

Another large militia, the Patriotic Movement for Central Africa (MPC), said it considered the accord "void." One of its founders had been given a minister's post.

Just hours after the ministerial list was unveiled on Sunday, the Popular Front for the Renaissance of the Central African Republic (FPRC), said it was leaving the government.

The FPRC did not specify whether it planned to remain part of the peace process, but charged the authorities with "bad faith, amateurism and incompetence."

It is the eighth attempt to bring peace to the CAR, one of the world's poorest and most unstable countries, since mainly Muslim rebels ousted president Francois Bozize, a Christian, in 2013.

France, the former colonial ruler, intervened militarily under a UN mandate as fears grew of a Rwandan-style genocide.

The Seleka rebels were forced from power and in February 2016, Touadera, a former prime minister, was elected president.

- Stifled hope -

Under the peace accord's provisions, Touadera agreed to form an "inclusive" government.

But in the team unveiled on Sunday, the ministers in sensitive key posts all kept their jobs, while six of the 14 armed groups obtained no post at all.

One of those left out, the Movement of Central African Freedom Fighters for Justice (MLCJ), a small group in the north of the country, warned the authorities "to look again" at the list.

The armed groups had also demanded that the prime minister be chosen from their ranks.

But the job was handed instead to Ngrebada, Touadera's former cabinet director.

"By playing at 'Let's take the same people and start over', the president of the republic ... has stifled all hope at birth," the FPRC said.

The deal was prepared in 2017 by the African Union and has the support of Bangui's partners, notably France, along with a 12,000-strong UN stabilisation mission, MINUSCA.

But militia groups, often claiming to defend an ethnicity or religious group, still hold sway over four-fifths of the country.

Fighting, typically for control of natural resources, has left thousands dead and forced a quarter of the population of 4.5 million from their homes.

Other provisions in the peace agreement include the launch of a "Truth, Justice, Reparation and Reconciliation Commission" within 90 days and the start of joint patrols by militia members and the security forces.

The agreement does not spell out any amnesty for militia leaders -- something that had been a stumbling block in past agreements. However, the president may exercise a "discretionary right to issue pardons".