The Central African Republic (CAR) has signed a military co-operation agreement with Russia, deepening relations less than a month after three Russian journalists were killed in the African nation.

Russian Defence Minister Sergei Shoigu said the deal would "help strengthen ties in the defence sphere" after a signing ceremony in Moscow with his CAR counterpart Marie-Noelle Koyara.

A UN arms embargo on CAR was lifted for Russia in 2017. Moscow sent specialists to train the forces and some security agents to be part of President Faustin-Archange Touadera's presidential guard.

The Russian journalists who were killed were investigating Russian mercenaries alleged to be active in CAR.

Russian and CAR authorities labelled the killing as a robbery, but exiled former tycoon Mikhail Khodorkovsky, who was funding the journalists' investigation, said the argument did "not stand up to scrutiny", the Reuters news agency reports.