"We are seeking peace, and in the agreement there are mechanisms which would allow us to continue to work," Touadera told reporters after meeting Pope Francis.

"We are committed to ensuring that this deal can bring peace to the Central African Republic (CAR)," he added.

Less than a month after it was signed, the Central African Republic's peace agreement is under strain after five militia groups on Monday either pulled out or rejected the make-up of the new government.

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

A new executive was formed on Sunday -- in accordance with the deal which called for an "inclusive government" -- but with all the main ministers remaining in post.

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".

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

Within hours three other groups announced they also rejected the peace deal or were pulling out of the new government.

The current peace process 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.

"It's a huge challenge," admitted Touadera.

"It's one thing to have an agreement, but it must be applied... and we need help from our friends," he added.

The Vatican, in a statement, said Pope Francis and diplomats had encouraged engagement to promote peaceful co-existence and "national reconciliation".