The CAR is experiencing relative calm since the accord was signed in February between the government and 14 military groups -- the eighth deal since the conflict erupted -- but clashes are still regular in the landlocked country.

"Sanctions will be strictly applied to all those who violate the provisions of the agreement," UN envoy Mankeur N'Diaye told several leaders and representatives of armed groups in Bangui in a follow-up meeting on the peace agreement.

"All that has been tolerated will not be tolerated from today," he said.

Despite the agreement, between 10 and 70 violations of the pact, including murders, rapes and kidnappings, are recorded each week by the UN Mission in Central Africa, MINSUCA, which has so far favoured a strategy of dialogue with rebel groups.

Several leaders of the most powerful rebel groups were present at the meeting, including Abdoulaye Hissene of the Popular Front for the Renaissance of the Central African Republic (FPRC), and Mahamat Al-Khatim, of the Patriotic Movement for Central Africa (MPC).

UN representatives, the African Union and the Central African Government also attended.

The UN discussions, which will continue until Saturday, aim to speed up the peace process.

Key issues include a disarmament and demobilisation programme for armed groups that signed the deal and the lifting of illicit checkpoints where merchants and traders are forced to pay tolls.

The CAR has been struggling to recover from the bloodletting that broke out when former president Francois Bozize, a Christian, was overthrown in 2013 by mainly Muslim Seleka rebels.

Since then, fighting has forced nearly a quarter of the country's 4.5 million people to flee their homes.