China's embassy in the Central African Republic has urged its citizens to avoid travelling outside the capital, Bangui, after a report that nine Chinese nationals were killed in an attack by militants at a gold mine outside the city.

The embassy said in a statement on Sunday there had been many “vicious” security incidents against workers of foreign mining enterprises in the area, and Chinese citizens still outside Bangui were requested to evacuate immediately.

Armed men killed nine Chinese nationals in an attack on a mine run by the Gold Coast Group, 25 km (15 miles) from the town of Bambari, its mayor said on Sunday, according to a report from Agence France-Presse (AFP).

"We have counted nine bodies and two wounded,” the mayor of Bambari, Abel Matchipata, told AFP. The attack happened around 5 a.m. (0300 GMT), he added. A security source confirmed the toll and the nationality of the victims, according to AFP.

Chinese President Xi Jinping has called for“severe punishment” of the perpetrators in accordance to the law, and said the safety of Chinese citizens must be ensured, the Chinese foreign ministry said in a statement on Monday.

In view of the security risks, the Chinese embassy warned Chinese institutions and citizens not to travel outside Bangui and in case of emergency, to contact the embassy to seek consular protection.

The security risk level in the Central African Republic, apart from the capital, was“red”, or very high, the Chinese foreign ministry added.

The ministry said it would work with governments and guide Chinese embassies and consulates to take further effective measures to fully safeguard Chinese citizens and enterprises in Africa.

There have been several attacks on Chinese nationals abroad in recent months, prompting embassies to issue warnings and safety alerts and conduct evacuations.